Author's Note:

This is the first time I've tried writing this pairing, so I hope their personalities come across well! Feedback on how to improve is always welcome.

For the curious, L'Hopital's rule is a calculus theorem that allows you to take the limit of a fractional function under certain circumstances when you might not be able to find the limit otherwise. Paul's Online Math Notes has a good explanation.

Chapter 1: Unexpected Visitors

"Let's see," Ichigo muttered, nibbling absently on the end of his pencil. "If the limit as x goes to infinity of f(x) is infinity, and the limit as x goes to infinity of g(x) is infinity, and I've got f(x) divided by g(x)…" He trailed off, staring down at his blank piece of paper as though it held all the answers of the universe. I know I need to use L'Hopital's rule here, but that would be a lot easier if taking the derivatives of both f(x) and g(x) didn't leave me right back where I started. Glaring at the massive textbook resting innocently on his desk, he sighed. Stupid calculus.

The orange-haired teen pushed his chair away from his desk, spinning to stare out of the window. He had a math test on Friday, a history test on Monday, and a chemistry test on Tuesday, plus mountains of other homework. His soul reaper duties had forced him to miss so much school that he was almost failing most of his classes, and had an insane amount of makeup work to complete. If he didn't pass these exams, there was no way he could pass the classes – and if he failed any of them, getting into a top university would be nearly impossible.

Ichigo rubbed his temples with his index fingers, turning reluctantly back to his desk. From fighting Aizen and every espada he could throw at me, to wrestling with math problems, he thought grumpily. I think I'd rather be fighting that psychopath again.

Out of nowhere, the stench of burning flesh filled his nostrils, and he flinched. Well, maybe not, he admitted mentally. Not if it meant losing control and nearly eviscerating his friends again. The image of Orihime's terrified face swam in front of his vision, and he shuddered. Actually, maybe peace sounds pretty good. He blinked hard, determinedly forcing away the memories that threatened to overwhelm him, and pulled his textbook closer. Alright, back to math. Taking his pencil out of his mouth, he began to rearrange his fraction in an attempt to get a more tractable set of derivatives.

You know that this peace doesn't suit you, the eerie voice of his hollow snickered in the back of his head. You need the thrill of the fight and the rush of the kill to feel fully alive.

"Shut up!" Ichigo snarled back. "We've had this argument before, and I'm not going to have it again!" He glanced at his alarm clock and groaned. Especially not when I've got another three hours of studying to do, and I've got to be up for school in six. He propped his chin on his hand, staring morosely at his textbook. It was tempting to simply give up and go to bed, but he refused to give in so easily. I didn't give up when I was fighting Grimmjow or Ulquiorra, and I'm not going to give up now, he told himself stubbornly. Though L'Hopital's rule was proving to be a more formidable opponent than either espada.

He managed another five minutes of work before a gentle tapping on his window distracted him. Shoving his textbook away, he rose and stretched his arms above his head before pulling his curtains back. "What now, Rukia?" he asked irritably, expecting to see the petite shinigami standing on the air, tapping her foot impatiently.

Instead, a buxom girl with vivid turquoise hair and sparkling hazel eyes waved at him cheerfully. Ichigo's mouth dropped open. "Nel?" he blurted out incredulously. The former espada grinned playfully at him. The ragged green top that she wore as a dress in her younger form strained over her voluptuous breasts, baring a toned midriff that flowed seamlessly into long, lightly-furred legs. Several minor cuts marred her fair skin, but didn't detract from her beauty. Her hooves – Ichigo double-checked, and nodded: yep, four hooves – pranced on the air outside of his window. The horns of her cracked helmet curved proudly over her shoulders; for some reason she had festooned them with streamers.

He hastily swung the window open. "What are you doing in your centaur form?" he asked curiously. Though Orihime had healed her after the war, restoring her to her full power, she still struggled to maintain her resurrection for too long. From what she had said, she actually preferred to remain in her little form unless the situation forced her to take an adult mien. Privately, Ichigo wondered if she simply wanted the freedom to act completely immature; she certainly took full advantage of it.

Nel turned sideways, and announced happily, "I've got a present for you, Itsyugo!"

At first, Ichigo couldn't believe that he had heard her correctly. The limp form draped across her back, dripping blood down her flanks, was unmistakably the former sexta espada, Grimmjow Jaegerjaquez. I would recognize that shock of electric blue hair anywhere. Grimmjow's white jacket bore numerous scorch marks, and his hakama were tattered.

Ichigo groaned and pressed his palm against his forehead. "Nel, please tell me you're not referring to Grimmjow," he begged. "Why are you carrying him, anyway? And why is he unconscious?" Nel had given him other 'presents' on occasion – most memorably, a hollow toad spirit that she had thought would make him the perfect pet. He had gently asked her to return it to Hueco Mundo, and she had agreed with a pout. Since then, she had settled for nonliving gifts, like a pretty stone, a shard of crystal, and a warped statue that must have come from Szayelaporro's lab. This was the first time since the toad incident that she had brought a living being with her. I really hope that's not the 'present' you want to give me, he thought glumly. But I'm afraid it is.

Nel shrugged fluidly. The motion did interesting things to her cleavage, but Ichigo barely noticed – his gaze was fixed suspiciously on Grimmjow. "He's unconscious because he challenged me to a fight, and lost. Badly," she added, a bit smugly. Ichigo raised an eyebrow, and she continued, "Which is also why I'm carrying him; I couldn't exactly ask him to walk on his own." Gentle condescension laced through her tone, but Ichigo didn't take offense. Getting angry with Nel was like getting angry with the wind.

The substitute soul reaper sighed heavily. "You still haven't answered my first question," he pointed out wearily. "Are you saying that you're…" he hesitated, "giving Grimmjow to me?" Never mind the ethics of treating a sapient creature like an inanimate object, he sighed to himself. What am I supposed to do with him? He could imagine Grimmjow's reaction when he woke up and found himself in the company of the soul reaper that he despised the most, and it wouldn't be pretty.

"Of course!" Nel chirped brightly.

"Of course," Ichigo echoed in an undertone. Fixing Nel with a stern gaze, he pointed out, "Nel, you can't give me a person as a present." In her adult form, she should already understand that. Actually, in her child form, she should comprehend it as well; her childlike form evinced a startling amount of knowledge. I'll never forget when she said that she was a masochist, he thought wryly. No five-year-old should have any idea what that means. Of course, he hadn't known the truth about her age until much later.

Nel shrugged again. "Fine then, not a present. Still, will you take him?" She widened her hazel eyes imploringly at him, allowing the crimson line over her cheekbones to accentuate the expression.

Ichigo resisted the urge to rub his aching temples – his headache had returned with a vengeance. Instead, he gritted his teeth, and asked, "Why do you want me to take him? In case you've forgotten, we don't exactly get along." That was a severe understatement.

Nelliel's expression sobered. "Because, if he stays in Hueco Mundo, he'll die," she said bluntly.

Ichigo cast a skeptical look at the unconscious arrancar sprawled across Nelliel's back. "Are you sure?" he asked dubiously. As the former sexta, only a few espada had been stronger than him, and most of those were dead now. So who could take him out?

She nodded sadly. "He's made a lot of powerful enemies, and I've heard rumors that several are planning on banding together to kill him," she informed him. Her lips quirked, and she added, "If that was all, I wouldn't care. But I don't want his death on my conscience. If the only reason they succeeded in killing him was because of his fight with me, well…" She trailed off, her eyes drifting away from Ichigo's as she glanced down. "And maybe I don't approve of their methods."

He grimaced. "That makes sense," he replied softly. After all, you did lose your place in the espada, and a significant amount of your power, because two of your opponents ganged up on you. The idea of such a backhanded, treacherous attack grated against Ichigo's sense of fair play. Fighting your opponents in an honorable battle was one thing. But no true warrior stabbed their opponent in the back to get revenge for their defeat in such a battle.

Nel gave him a megawatt smile, turning up her charm. "So you'll take him then?" she asked hopefully, clasping her hands in front of her chest.

"I guess so," Ichigo muttered, already regretting it. He glanced suspiciously at Grimmjow, who remained motionless. "But only if he wants to stay," he warned her. "I won't keep anyone here against their will." Since the chances of Grimmjow voluntarily remaining with him were slim to none, he wouldn't need to deal with the violent-tempered espada for too long. Only until he wakes up; then he can return to Hueco Mundo. That'd be best for everyone. Given the rapid rate of healing possessed by most arrancar, he would probably awaken within the hour.

Nel clapped her hands joyously. "Oh, thank you, Itsyugo!" she gushed excitedly. "Thank you!" She maneuvered her front legs up onto his windowsill, angling her body so that Grimmjow's limp form was within easy reach. Ichigo carefully reached out to touch the espada lightly on the shoulder. When he didn't stir, the substitute soul reaper took a firmer grasp and hauled Grimmjow into his room. The espada grunted as his legs struck the edge of the window, but otherwise made no sound.

Nel's hooves, on the other hand, clattered loudly against the windowsill as she backed away. Ichigo winced. "Careful!" he hissed, gesturing vaguely around his room. "Don't let my family hear you!" While his sisters might be enamored by her charming personality and equine aspect, his father would not be so enthralled by the sudden appearance of a powerful arrancar.

Nel blushed. "Sorry about that," she whispered. With a wave of her hand, her back legs dissolved into smoke, which wreathed her briefly in a hazy cloud of reiatsu. When it cleared, she had regained her normal adult form, complete with zanpakuto sheathed at her side. From somewhere – Ichigo wasn't quite sure where, as her outfit barely concealed her assets, and surely couldn't have hidden an object bigger than a paperclip – she produced the mangled remains of a zanpakuto. "He'll want this when he awakens," she informed him in a low voice.

Ichigo nodded, accepting the shards from her. The light blue hilt and crooked 'S' shape of the hand guard marked at as Grimmjow's weapon, if the hum of reiatsu emanating from it didn't give it away. Several inches of blade protruded from the hilt; the remainder lay in three jagged pieces. "What happened to it?" he asked curiously.

She chuckled. "He tried to block my cero doble with it, after firing a gran rey cero at me." Perching on his windowsill, she swung her legs idly over the street below. If any passerby could have seen her, she would have given them quite a show.

"That would do it," Ichigo acknowledged, gently setting the shards on his desk. Nel's cero doble power reflected and exponentially magnified the ceros of her opponents. If Grimmjow had attempted to use a gran rey cero – the strongest type of cero that Ichigo knew about – it wasn't a surprise that Nel's return attack had shattered his blade.

Nel grinned cheerfully at him. "Again, thank you for looking after him," she said seriously. "I hope he won't be too big a burden." She dropped out of his window and trotted over to his side, staring down at Grimmjow with assessing eyes.

Ichigo shrugged. "He can't be that bad." After all, he'll be out of here like a cat with its tail on fire as soon as he wakes up.

The former tres espada giggled. "Hopefully!" Before he could react, she gave him a quick peck on the cheek. "You're a good man, Itsyugo," she said softly. He blinked at her, stunned, and she hopped out of his window. "Well, bye!" she called, waving furiously at him as she sonidoed away.

Ichigo hung his head as he felt her spiritual pressure vanish into the folds of a garganta. Damn it, Nel, why now? he wondered tiredly. Then he shook his head. But there's nothing to be done until Grimmjow wakes up, so I might as well continue working on my math. He grimaced. Give it an hour, and I'll need a break for sure. The ruckus that Grimmjow would surely cause would come as a welcome distraction.

An hour later, however, and the blue-haired espada still hadn't awoken. He was, however, making little growling noises at random intervals, which served to thoroughly distract Ichigo from his math homework. Is he asleep? Ichigo wondered, as another soft snarl echoed through the room. "Grimmjow, wake up," he called softly. A quiet growl, almost a purr, answered him. Fed up, the substitute soul reaper shoved his chair back and stalked over to Grimmjow's side.

"C'mon, wake up," he muttered in frustration, tapping his foot impatiently. "You can't just lie there all night." What if his father came in? Or worse, his sisters? Besides, I need to finish my calculus homework, he thought grumpily, and I can't focus on that while you're lying there, bleeding all over my bed. He shook Grimmjow's shoulders, careful not to open his wounds any further.

Slowly the espada's eyes fluttered open. "Huh?" he murmured dazedly. "What… Where am I?" Then his azure eyes fixed upon Ichigo. "Damn it, shinigami, what the hell is going on?" he spat, wrenching his body into a sitting position. The move split open the wound in his gut, right above his hollow hole, sending rivulets of dark crimson blood dripping down his bare torso.

"Lie back down, you idiot," Ichigo snarled back. "I don't want your blood all over my bed, thank you very much." He pushed firmly on Grimmjow's shoulders, and the espada reluctantly allowed the pressure to guide him back down.

The defenseless position didn't dampen the fire in his eyes, though. He glared at Ichigo as he growled, "So, Kurosaki, why am I here, in the living world? More like, why am I anywhere near you?"

Ichigo threw up his hands. "Because Nel dropped you off here, semi-conscious and dripping blood. I guess she doesn't want you to die, or something, and you've made some powerful enemies in Hueco Mundo." Not that the latter was a surprise. Grimmjow would challenge anyone to a fight if it promised to provide entertainment. And I suppose Hueco Mundo must get pretty boring without something interesting to do.

Grimmjow sneered. "Survival of the fittest. She should have left me in the sand where I fell, if she was too weak to kill me herself." He rolled his eyes. "But then she's always been too soft for an arrancar. She wouldn't kill Nnoitra, either, and that asshole certainly deserved it." He turned his glare back on Ichigo. "But that doesn't explain why she dumped me with you." He gestured angrily at the room as he spoke, wrenching open the gash in his shoulder. Scarlet droplets spattered the blankets underneath him, and Ichigo sighed heavily.

"I don't know, either. I've got a calculus exam Friday; I don't have time to deal with you." He cast a baleful glance at the heavy textbook resting on his desk. And I'll probably fail it even if I do study; the average on the last test was a 47. So I don't need any distractions. He returned his focus to the espada shifting uncomfortably on his bed. "So, if you can open a garganta and return to Hueco Mundo, I think we'd both be happiest."

Grimmjow snorted, running his fingers over the slash in his abdomen. "Wow, she really got me good," he muttered, before looking up at Ichigo. "Just give me Pantera, then, and I'll get out of your way," he ordered arrogantly.

Ichigo gestured to the remains of the blade, sitting next to his hated math textbook. "Right there."

The espada heaved a frustrated sigh, an odd expression in his cerulean eyes. "Well, fuck. So much for that, then," he muttered angrily.

Ichigo raised an eyebrow. "What, can't you go back to Hueco Mundo without your zanpakuto?" he asked coolly. "And stop swearing," he added. "I don't want my sisters to hear that kind of language."

Grimmjow chuckled incredulously. "Always protecting someone, aren't you?" he asked rhetorically. "And, no, I can't create a garganta with Pantera in that sort of condition. We need our full powers build a stable gate." Even so, he reached out and touched the hilt with possessive fingers. His expression softened momentarily, turning almost peaceful, before his lips twisted into another sneer. "Guess that means I'm stuck here."

Oh, please tell me this is a joke, Ichigo thought in horror. He slumped down into his chair, cradling his head in his hands. "If you're anything like a shinigami, your zanpakuto should mend itself as your body…" he muttered.

"Yeah, yeah, I know all that," Grimmjow interrupted rudely. "It's not like I wanted this, you know."

Ichigo lifted his head. "Wait, so if only arrancar at full power can create garganta, how do all of the hollows get here?" he asked in confusion. He'd seen hollows emerging from rifts in the sky numerous times. Admittedly, those rips in reality had looked far less stable than the neat garganta that the espada could create, but that should have been a matter of ability. The more powerful the hollow, the cleaner the portal looks, he reasoned. But lower-level hollows can still reach this world. So why can't Grimmjow return home?

The blue-haired espada leveled a withering look at him. "Don't they teach you anything?" he asked condescendingly. Pulling himself gingerly into a sitting position, he explained, "The lesser hollows are mindless beasts, incapable of the delicate magic of a garganta." He rolled his eyes, ignoring Ichigo's exasperated snort. Assuming a lecturing tone, he continued, "The barrier between your world and mine isn't like a rock wall; it's more like a sponge. Natural rips occur frequently. The hollows you see simply wait for one to appear, and travel through it while it remains open." He tapped his fingers on the hilt of his zanpakuto. "But if you want to arrive where – or, more importantly, when – you want, you need one of these." His expression turned distant, and he scooped up the remaining pieces of his sword. The silvery metal shivered in his hands, as if it was eager to be reunited with its master.

Ichigo's shoulders slumped. "Well, I guess you're stuck with me, then," he mumbled. Great. Now how am I supposed to study for my math test? He glanced up to see the espada regarding him with a peculiar expression. "What?" he demanded.

Grimmjow shrugged fluidly. "Nothing," he replied shortly. He ran his fingers though his hair, spiking it into crazy angles. "Just, in the desert, there's no way a hollow would help a wounded enemy, much less one who tried to kill him multiple times." He smirked cynically. "You shinigami are so weak."

Irritated, Ichigo leveled a glare at him. "It's because of my 'weakness' that you're alive right now, so don't complain," he ordered.

The espada snickered. "Oh, I'm not complaining, just pointing out a fact," he purred. He propped himself up on an elbow, seemingly unconcerned by the way the blood trickled out of the hole in his shoulder. His eyes narrowed as he scanned the room, eventually landing on Ichigo's bedspread. "So, why do you have a quincy symbol on your blanket?" he asked conversationally.

Ichigo felt a dull flush creeping up his cheeks. "It's not a quincy symbol," he snapped hastily, refusing to look Grimmjow in the eye. It really wasn't; he had owned the blanket since he was ten – long before he knew about the various spiritually-aware races. Though it did look suspiciously similar to a simple quincy cross.

Grimmjow's smirk broadened. "Uh-huh," he replied smoothly. "It has nothing to do with that skinny kid with glasses who got his ass kicked by Szayel." He sneered, and muttered, "Good riddance to that pink-haired freak." Ichigo rolled his eyes as the espada prodded at the gash in his lower abdomen, which ran perilously close to his hollow hole. Scarlet blood welled out, disrupting the scab that had been forming.

Grimmjow poked the wound again with a dispassionate expression, and Ichigo heaved a sigh. "I can call Orihime to heal you, so you can go back home," he offered.

For a moment, Grimmjow's expression turned speculative. "She does good work," he acknowledged. Ichigo was reaching for his cell phone when the espada continued, grimacing, "But you might not want to do that."

"Why not?" Ichigo demanded. Orihime had rescued him from the brink of death, restored Grimmjow's arm, and patched up any number of lesser wounds. She could even fully restore his spiritual pressure. Grimmjow's injuries wouldn't make her blink an eye.

Grimmjow snorted cynically. "You really think she wants to see another espada, at this point?"

Ichigo froze. I hate to admit it, but he's right, he thought slowly. She didn't handle a return to normal life too smoothly; I don't want to bring up any bad memories. After her captivity, Orihime had withdrawn from her normal, cheerful self, barely speaking or eating for weeks. Yoruichi had eventually talked to her, and she now bounced around like usual, but she hadn't seen a single powerful hollow since the final battle. Seeing Grimmjow might just tip her back into whatever state she was in. He was shocked that the temperamental espada had thought of that issue.

His surprise must have shown on his face, for Grimmjow bared his teeth. "Don't get any ideas, Kurosaki," he warned. "It's not like I care about the woman, after all. I just don't want a hysterical girl screaming in my ear." The glimmer of concern in his eyes belied his callous tone.

Ichigo rolled his eyes. "Fine," he muttered. "But if you're going to stay here, you're going to let me bandage your wounds." His tone brooked no disagreement.

"Why?" Grimmjow demanded hotly.

Ichigo gave him a stern look. "Because you're already bleeding all over my bed, and I don't want your blood getting everywhere," he pointed out dryly. He had no idea if an espada's blood was even visible to normal mortals, but he didn't want to take any chances. Growing up in a medical clinic had taught him a disturbing amount about various blood-borne pathogens, and his father had warned them numerous times about the dangers of contamination. Never mind the risk of infection for open wounds. Leaving an injury untreated went against all of his training.

The temperamental espada glared at him, but Ichigo didn't back down. He held Grimmjow's gaze calmly, ignoring the fire that threatened violent retribution if he didn't give in. Finally Grimmjow looked away and sighed. "Fine," he grumbled. "Do whatever you want." He did his best to convey, wordlessly, that it really wasn't that important of a decision, after all.

Biting back a chuckle at the espada's aggrieved expression, Ichigo headed out of the room to fetch some bandages. "Don't move or make a sound while I'm gone," he warned over his shoulder, hand on the doorknob.

Grimmjow waved a hand. "Yeah, yeah." Ichigo rolled his eyes as he shut the door firmly behind him. He had little faith in the espada's promise of good behavior, but he wouldn't be gone long. If he tries to start any trouble, Karin will squash him, Ichigo chuckled to himself. His little sister had become even fiercer after their father had reluctantly revealed the truth of his history to the girls. She's developed quite a bit of spiritual pressure, too. Even their father was cowed by her uncompromising stare.

Ichigo rummaged through the drawers of medical supplies down in the clinic, one ear cocked for any sounds coming from upstairs. To his relief, the house was blessedly silent. Neither Grimmjow nor his family made a sound as he grabbed a handful of sterile bandages and hurried back to his room.

Grimmjow's eyes widened as Ichigo dumped the medical supplies on his bed. Along with bandages, the substitute shinigami had grabbed antiseptic wipes, needle, and thread, though he doubted that Grimmjow would allow him to use the latter. "Where'd you get all that stuff?" the espada asked incredulously.

Ichigo lifted an eyebrow. "My father runs a medical clinic; where do you think I got it?" He shoved the bandages to the side, ripping open one of the antiseptic wipes. "I don't know if your wounds can get infected, but there's no point in taking chances," he explained calmly as he took a seat on the edge of the bed. When Grimmjow huffed, he added, "Besides, you've got blood smeared all over you; that, at least, needs to be cleaned up." Preferably before it made an even bigger mess.

"Stupid human customs," Grimmjow grumbled. He grabbed the antiseptic wipe from Ichigo, and snarled, "I can do that myself. I'm not a helpless kitten, you know." He dabbed awkwardly at the gash in his shoulder, wincing at the other wounds decorating his torso pulled against the motion.

"I'm not saying you're helpless," Ichigo snapped back, reclaiming the wipe, "but you're just re-injuring yourself by moving around too much." He fixed Grimmjow with a gimlet stare. "Now stay still, damn it!" He pushed Grimmjow down with a hand on his uninjured shoulder, careful to avoid putting too much pressure on the small burn marks dotting his chest. It looked like he had tried to block a cero, only to have it fracture around his blade and splatter him with fiery reiatsu. Ichigo couldn't do anything about the burns, but the espada's rapid healing would take care of them soon enough.

Grimmjow hissed harshly between his teeth as Ichigo dabbed at the blood splashed across his chest. As Ichigo carefully cleaned the area around the stab wound in his shoulder, he complained, "Fuck, that stings!"

"You're worse than a little kid," Ichigo replied absently. He didn't like the way the edges of the gash puckered; puncture wounds had a tendency to get infected. He could see a sliver of white bone, barely visible under the gore, at the heart of the wound. Nel is a vicious fighter with that spear of hers, he mused, ignoring Grimmjow's hisses as he ran the antiseptic wipe over the torn flesh. This will take a while to heal.

Thankfully, that appeared to be the worst of Grimmjow's injuries. The slice above his hollow hole, while deep, managed to avoid his internal organs. Actually, Ichigo wondered, carefully running the wipe along the edges of the gash, do arrancar even have organs? How would that work with their hollow holes? As far as he could tell, shinigami bodies functioned similarly to human ones, but he knew almost nothing about hollow biology.

He considered asking Grimmjow, but the frustrated expression on the espada's face dissuaded him. If I annoy him too much, he really will start a fight, injuries or not, and I really don't want to deal with that, he reasoned. Karin would murder me, for one thing. So he continued mopping up every speck of blood in silence, ignoring the espada's glower.

That silence was broken a moment later by Grimmjow's hissed curse. Ichigo looked up, startled by the strange note in the espada's tone. "Are you alright?" he asked cautiously, hastily lifting the antiseptic wipe away from the gash in Grimmjow's abdomen. "Did I hurt you, or something?"

Grimmjow snorted arrogantly. "Yeah, right. As if."

Ichigo exhaled heavily and glared at the espada, who stared back at him with glowing sapphire eyes. "You could be more polite, you know," he pointed out in an irritated tone, returning to his self-appointed task. "I could have asked Nel to dump you back in the desert." Grimmjow huffed. Rolling his eyes for what felt like the thousandth time that night, Ichigo took a final swipe at the smears of blood around the espada's hollow hole, carelessly letting his fingers brush against its edge.

Grimmjow breathed another curse. "Fuck, Kurosaki, are you done playing doctor yet?" he growled. A lascivious leer spread over his face, and he added, "Though if you enjoy it so much, I bet you'd look quite fetching in a little nurse's outfit." His reiatsu flared with amusement, filling the room with the faint scent of wintergreen and mint.

It took all of Ichigo's willpower to stop himself from punching that irritating smirk off of the arrogant espada's face, but he managed – barely. Quickly flaring his own power to mask the obvious taint of hollow reiatsu, he snarled, "Reign it in, will you? I don't want my family to know you're here." Seizing a handful of bandages, he began to wrap them securely around Grimmjow's abdomen.

The espada heaved a put-upon sigh, but furled his reiatsu. "You're no fun," he complained. Ichigo yanked on the bandages a bit harder than necessary, and received a dry glare in return.

Once he had finished, Grimmjow sprawled indolently on Ichigo's bed, eyes sliding halfway closed. He really is just like a cat, the substitute soul reaper thought with carefully concealed amusement. He can take up more space than physically possible. Turning away to hide his smile, he informed Grimmjow brusquely, "You can sleep in the closet. There are blankets, and I think Rukia left a lamp in there the last time she came to visit." Which, of course, she hadn't bothered to ask permission for. By now, Ichigo had resigned himself to her antics.

Grimmjow eyed the space skeptically. "There's no way I'll fit in there," he drawled.

"Not my problem," Ichigo shot back, dropping into his chair with an audible thump. "I have math homework to do, so you can either stay there or find somewhere else to hole up until you're healed." He rubbed his aching temples with one hand, staring in frustration at the newest incomprehensible problem in front of him. Find the values of x where the given series converges, and prove that it converges conditionally, not absolutely. Did we even learn how to do this?

Much to his dismay, Grimmjow swung himself off of the bed and sauntered over. Draping himself over the back of Ichigo's chair, he asked, "So, what are you working on?" His breath ruffled the messy strands of Ichigo's hair, making the substitute shinigami shiver.

"This," he replied curtly, shoving his textbook in Grimmjow's direction. "And I'd like to concentrate, so shut up." He practically growled the last two words, and Grimmjow snickered.

"Better you than me." He prodded the book with a sharp fingernail. "Why do you have to do all of this anyway?"

It was a question Ichigo had asked himself many times. It wasn't like he was going to ever use it again, after all. Unless I wanted to become an engineer or something, calculus is useless to me. He wasn't sure what he wanted to major in yet – his dad advocated for biology, while he was more tempted by art – but he was sure of one thing: he wasn't going to need calculus! But he didn't feel like explaining the entire Japanese school system to Grimmjow, who would surely use it as an excuse to mock him. "You know what, let's just go to bed," he suggested wearily. Math can wait until tomorrow.

Grimmjow shrugged, making no protest as Ichigo snapped his textbook shut and pushed his study guide away. He did grumble when Ichigo shoved him, none-too-gently, in the direction of the closet, but he finally slid the door open and crawled inside. Ichigo heaved a sigh of relief. Finally, peace and quiet. He flicked off the light and flopped onto his bed, fumbling for the blankets. Usually, he would change into pajamas, but he didn't trust Grimmjow to behave himself if he got bored. And I'm not chasing him down wearing only boxers if he decides to go wandering.

The rustling sound of Grimmjow arranging the closet to his liking stopped, and Ichigo mumbled sleepily, "Good night, Grimmjow."

A long time later, after Ichigo had given up waiting for a response, Grimmjow murmured, "Good night, Kurosaki."