Disclaimer; Everything except the plot belongs to JK Rowling and Co. Not me.

Author's Note: I love Severitus/Guardian fanfiction, this is one of those. It's not by any means original, but I really wanted to see him relate to all the kids in the DA. This is a kind of 'what-if' Severus found himself helping out the DA. But the main focus is on an eventual Harry/Severus Guardian/Mentorship.

Chapter One

It happened to be pure coincidence that led Severus Snape to witness an incident that would later be revealed as a defining moment for him. He did not know it at the time, nor even weeks later, how the seed had planted in his mind. He did not know how much one seemingly insignificant scene could change what were once deep-seated convictions. Over time (though, admittedly, it was quite some time) Severus would find Harry Potter was much more like his mother than his father.

If he had known where his life would lead following the fateful winter's day, he would have avoided it at all costs - providing he believed it in the first place.

At the time of the fabled event, Severus' beliefs had barely budged. They had been slightly - very slightly - dislodged. A little out of place. Not enough for him to actually consider that his opinions were... wrong. No, that would be absurd. But it was enough for him to be curious. And curiosity for any spy naturally led to espionage. Though spyingon a student was admittedly kind of pathetic, Severus was unable to refrain, so intrigued by the behaviour of a boy who should - in his mind - never, ever have reacted as he had.

The incident in question was not even something out of the ordinary. Not for Harry.

But for Severus, it was the moment his beliefs that the Boy-Who-Lived was a carbon copy of his replusive father were shattered.

It had been one of those days. The kind that were long and tedious and by mid-evening Severus was contemplating the bottle of firewhiskey that called to him. Between restocking the Orders depleted stores, teaching, and brewing the wolf's precious elixir, he had very little time on his hands. The brewing in itself, despite the magnitude, would have been relatively smooth sailing, was it not for the numerous interruptions. Between disgruntled Slytherin's, a suspicious 'High Inquisitor' and Albus, he had botched more than his fair share of potions. It was frustrating, to say the least. By the time he had finished with the werewolf's precious elixir, he was famished.

Late for the evening feast but unwilling to be served leftovers by the talkative house elves, Severus' had no choice but to make a delayed entrance.

That was when he overheard what had his hackles rising. Raised voices that he vaguely recognised, and a jeering tone that was unmissable. Halting in the empty halls, he sighed minutely and closed his eyes for a brief moment. Muttering an annoyed, "Merlin, give me strength," he turned on his heels, to face an additional hindrance to his day. He knew those tones for what they were. Taunting. Teasing.

Bullying.

Effected by harsh childish antics himself when he was a student, it was something he would not tolorate from anyone. His Slytherins had learnt that early on in their school years, though he could think of some that still thought themselves above his demands. The other houses were less strict and the Heads of House oblivious to most teasing as though they could not fathom the possibility.

Gryffindors were the same. The worst, Severus could speak from experience. It was not a surprise when he turned the corner to see three Gryffindor boys taunting a visibly smaller, female Ravenclaw. Two of the tormentors were seated on the large, natural crevasses in the old walls, where the stones did not fit evenly, as a consequence for having been removed or replaced for various new rooms being erected. The boys looked like they had gotten comfortable, as though they had been waiting patiently for this opportunity.

The Ravenclaw - Miss Lovegood, he recognised grimly - was oft a target of bullies. She dodged the wrong side of eccentric, and it put her squarely into the attention of those willing to exploit vulnerabilities for their own entertainment. The young girl was at the opposite end of the short hallway, on her way towards the unseen Professor, presumably on her way to a late meal not unlike himself. He could see the skip in her step, even as the students perched on the wall were singing a jeering edition to an old rhyme at her. She looked entirely immune to their bullying, almost unaware of their presence, and Severus was grudgingly satisfied with her strength.

Of course, they had been waiting for this moment, they were not going to be satisfied with what little entertainment they had gotten. Their pathetic attempt at intimidation was going to turn nasty.

Moments later and his fears were confirmed, as the third boy leapt from his windowsill on the adjacent wall before Miss Lovegood could pass him. He was in front of her within minutes, blocking her bodily.

With his back to Severus now, he could not see either of their reactions to each other, but the calculated amusement on the faces of the boys watching - no longer singing, thank Merlin for small mercies - was quite revolting. How he would relish the opportunity to punish each one of them.

Though the professor did not suspect it at the time, Luna Lovegood would have been able to take them down with a simple wave of her wand. But she had been unprepared for an attack so close to her dorm room. Trusting enough to believe herself protected inside the walls of her school, her wand was tucked away in her sleeve.

She had been on her way to dinner when they accosted her. They had been waiting, she knew, and it could only be for one reason. It was late, they were late enough for tea that the food would already be on the table and the students half way through it. While tardiness was not uncommon for a Ravenclaw, the Gryffindors were normally good timekeepers. That in itself was suspicious enough, but the look of unsavory glee told her all she needed to know.

Her recent sparked friendships with the famous trio and his cohorts of Weasleys had given Luna a relief from being a real target for quite some time. There was still the occasion teasing, but no one accosted her as such. Apparently very few people were willing to risk the wrath of Harry or, worse, the Weasley twins. But she had not forgotten the usual drill.

Content to ignore the abuse, the younger student tried to pass by their taunting without a glance in their direction. It did not occur to her, though it had to the teacher watching, that they would not like to be disregarded. They had been waiting for the opportunity, after all. Would not want to waste it.

It was a shock, then, when the older boy jumped into her personal space. Luna was forced to stop short. "Please move." She requested her tone perfectly relaxed. Say what they want to her, she was hungry.

The one in front of her laughed, and Luna frowned, indignant. But only for a moment. Scowling took up muscles.

The aggressor was sixth year, she recognised him from the few times she had been hidden from Umbridge inside the Gryffindor common room. He was usually hanging around the twins' best friend. Tony or Terrance or something. He had a face that was pretty and young until it turned ugly with a scowl. Without replying to her request, he said, "Where you going, Looney?"

Was that not obvious? Deeming not answering was the best solution, Luna side-stepped, endeavoring to go around him, but he followed the maneuver with a menacing smirk. She frowned once more, but it smoothed out almost instantly. It was frustrating, if only because she wanted food.

Luna heard the loud stomps as the other two Gryffindors jumped from their makeshift seats, and she realised they were going to surround her. Trap her. Food now out of her mind, the sudden surge of helplessness spurred her into action.

It was surprise more than strength that allowed the slight Ravenclaw to barge past her physically larger peer. A pointy elbow in his ribs and he backed off nicely.

He regained his bearing quickly. Darting out a long arm, Thomas grasped at her retreating back. He managed to catch her long ponytail, and yanked hard. She let out a short yelp. The momentum of a painful tug threw Luna backwards, almost into him.

He released his grip on her hair and she stumbled in a half-circle to face him. Before she had a chance to regained her equilibrium however, he shoved her, twice. Hard. The forceful blows directed her into the hallway's wall.

Her hands automatically flew in front of her face, protecting her head from a nasty collision against the hard stone.

Without respite, he was in her personal space again.

Pressed flushed against her exposed back, Luna shuddered in horror and encompassing fear. He was too close and lingered too long for that to not be an implication of his intentions. His hands pressed on the wall either side of Luna's head. Although she could not see it, Luna could feel his face inches from her own, his breath tickling her ear. "What's the rush, Looney?" He breathed, the words tinged with his grin.

Frustrated by her own helplessness, Luna twisted in his makeshift prison so she was no longer facing the wall, but Toby. Her back against the wall now, she felt the cold seep through her thin shirt. Should have worn a jacket, she mused to herself, desperate to buried her terror behind her logical mind. She was a Ravenclaw, for goodness sake, she could take down an uneducated idiot, sixth year or not.

The movement dislodged the wand tucked in her sleeve, and she did her best not to smile in triumph. Subtly, Luna tried to pull it forth. If only she had not listened to Harry's concerns. Keeping in behind her ear was much more effective when she needed it immediately. She could have easily jelly-legged jinxed all of them if she had that handy. It would probably be beneficial for the DA to learn some wandless hexes.

A sharp grip on her wand-grabbing wrist caused her to frown petulantly.

Tony was shaking his head at her, like he had some reason to be disappointed in her.

The boys snickered, one of them crooning a drawn out 'oooh'. The other called an unfrendly, "Come on, Looney, we just want to talk." Timmy tried to look amicable, but it came out looking more like a sneer. Luna wrinkled her nose in disgust. "We've decided you need to talk to Harry for us."

She froze. What? That was not something she had been expecting. Harry was often a focus of conversation... pretty much everywhere, but she had no real connection to him apart from their budding friendship. If someone was going to 'talk to Harry' as some kind of substitute, would it not be more appropriate to speak to Ron or Hermione? Or the twins... he was in the twins year.

"We want in on your little secret." He was demanding.

Luna shook her head. "There's no secret."

The neutral sneer on his face turned vicious as he shook her, just a little. "Don't lie to me. We know what's going on. We. Want. In. You're going to talk to Harry for us."

"Nothing to talk about."

"Looney-"

"You're...Lions talk to Lions." She muttered, annoyed and frightened.

"Yeah," He drawled in an impatient tone, as though she should have known that was a stupid reply. "Like we hadn't already tried that, idiot."

It just shuttered her resolve. If the sixth year Gryffindors that were subtly 'enlisting' whom they trusted in their own year did not think them worthy, they were not going to get in. And it was utterly pathetic to be asking a fourth year student to get them in. A student whom they've never spoken to apart from the occasional jeering. Harry would be instantly suspicious.

"Just talk to Harry, put in a good word."

"No."

There was a long pause. Hard eyes locked with Luna's steady, bright gaze. She did her best to not to back down, until his gaze drifted, lower, and this face twisted to a leer as he leaned in even further, his body flush against Luna's. To her dismay, Timothy's free hand slid from the wall to brush her hair out of her face. "You're awful pretty, Looney." It was a compliment, but it sounded like a threat, and she shuddered at the implications. "From what I've seen, you like to give the rest of us Gryffindors some, don't you think it's my turn?"

Luna trembled, implications turned to outright statements. His turn. She felt her own hands shaking, the dread now encompassing her and churning her stomach. How could he even suggest... that. Feeling herself welling up, Luna strove to get a grip on her emotions. She needed to be strong, to get out of dodge before it got even more out of hand. "Rumours. You shouldn't spread rumours." She muttered, and then pursed her lips before more indignant comments escaped them.

"Looney-"

"Get off me." She demanded, suddenly angry in her own fear.

"Not a chance, Honey." He growled, "How 'bout we take this somewhere else, huh?"

"Where's your precious Voyuraptors now, Looney," One of the nameless boys was laughing, it was loud and disgusting sound. "They all gunna get us?"

Snape watched with a growing temper. He had been irate enough at the sight of three on one younger student, but shoving her like that, assaulting her like that, talking to her like that, he was fuming. If he had less control, he would have hexed them into next week. It had been difficult to stand back and let them harass her, but Snape had learnt the hard way how to deal with bullies like these. If he terrified them too early and did not give them a chance at playing the twisted little games, it would be a later date when they would hunt down their target. Since a professor had broken up their fun, it would be hidden in the shadows, not out in the open hallway where they considered themselves invulnerable. And, it would be more vicious, more merciless than ever.

By hanging back for a couple of admittedly long minutes, it had also given Lovegood a chance to defend herself too. And while she had been dignified and levelheaded, manpower and physical strength worked against the young witch. He was all but sure it was time to step out of the shadows, sentence the Gryffindors to detention for endless months of scrubbing floors and cutting out dead toad's heart's and handling harmful ingredients barehanded. With expelling out of the question as he had no control over the Gryffindor's and Albus' unconditional belief in his precious Lions, Snape would work the boys into the ground. He just hoped he was not too late, and Miss Lovegood not too disturbed by the actions of the twisted little boys.

Except, before he had a chance to make his presence known, Potter showed up.

And Snape found a light at the end of this dismal tunnel. A perfect opportunity to catch Harry Potter bullying. Sexually harassing, even. Revenge may have been fickle, but currently Snape reveled in it.

Slinking back to the edge of the corridor, Snape had perfect view.

Harry came from the opposite end of the short hallway. The same way Luna had come from. It was curious, if only because it was the a dead end, the corridor leading only to the Ravenclaw common room on the right and a small library on the left. Snape did not linger on that thought however, for there were many possible answers and he cared for none except making sure the boy got what he deserved.

The professor had no doubts that the boy would join his precious Gryffindors in taunting Luna. Even if he didn't join in, he would watch or laugh or -

But he didn't. And Snape observed Potter taking in the scene, his eyes falling and resting on the Ravenclaw. Even from across the short hallway, the flash of relief and fury in his eyes was unmistakeable.

None of the students had yet to notice the famous Gryffindor, so when he called a fierce "Luna?" the boys jumped half a foot. After a heartbeat they realised it was a fellow student not a teacher. It surprised Severus that they still looked contrite. Afraid, even. The boys who had not laid a hand on Luna, glanced at each other over the head of their friend. They looked... uneasy.

Luna, still pinned to the wall, had a different reaction all together. A reaction that had Snape reeling, dumbfounded. She smiled. With relief.

The idea that she would be happy that Potter had turned up, was not something that the professor could wrap his head around. He was a bully and a coward, just like the rest of them. Just like his father.

But she smiled, nonetheless. At Potter.

How could she be relieved?

Severus would even say, when she turned the smile back to her assailant, her smile had a hint of mocking to it. If it was anyone but the equable Luna Lovegood, of course.

When she lolled her head to look at the young Potter, Severus frowned. It didn't make sense. If there was one person in the school a bully would target, Luna would be the one. Though pretty and friendly, 'Looney' was a fitting nickname. He would never have thought James Potter's precious child would be anything but nasty to her.

She drawled a friendly, "Hi, Harry." There was no indication of distress in her voice.

Harry did not smile. His jaw clenched audibly, in fact. Lily's eyes were piercing his fellow housemates with a staggering glare. He stood in the theshold of the doorway, wand in hand but lowered, fist clenched around it. "Terry," he bit out, spitting the boys name like it was a disease, "get your hands off her before I remove them." He demanded.

Terry complied, jumping back as though it burned, "Harry-"

"Don't." He ordered, not looking at him. One by one, Harry stared them down. "Three against one. Very courageous of you." His voice dripped with scathing sarcasm and Severus wondered if he had learnt that tone from himself.

There was a moment of awkward silence.

"It was only a bit of fun, Harry," The blonde boy in back piped up.

Harry turned a murderous glare on him. "Does Luna look like she finds this fun?" He spat. The blonde shook his head frightfully. When Potter's sharp gaze fell back on the main aggressor, his eyes narrowed dangerously. With pursed lips, Terry did not speak, only backed up further from the young Ravenclaw. "You lay another fucking hand on her again, Wyles, and I'll make you wish I'd Avada'd you."

Snape's jaw dropped. Unable to regain his own composure, Severus was glad he was not being observed. The raw ire in the boy's voice would have had even Albus stopping short. Not only was he defending the girl, he was furious at her expense.

For the first time, Severus saw more than James Potter in the man's son. The boy, bright eyes blazing with anger, reminded him of a similar incident he would rather forget. The boy's mother, barely a year older, demanding her justice for Severus himself. Pushing back the regrets from that fateful day, he was unable to refrain from recalling the betrayal on her beautiful face after he uttered that foul word to her. Gritting his teeth, he pushed the scene into a deep, hidden hole in his mind. She was dead, there was no point bringing up unwanted memories.

He was willingly pulled from his train of thought as Potter quietly warned them, "I'm sure Professor Flitwick would not be pleased to hear sixth years were attacking his students. Nor would McGonagall." Potter sounded as though he was doing his best to repress his anger.

Appalled, all of the bullies seemed to have forgotten Potter's foreboding threat and three incredulous voices all spoke at once.

"What? No, but Harry, you can't -"

"You wouldn't do that, we're in your house!"

"She'll take points!"

"I don't give a damn!" Harry hissed loudly, interrupting any other attempt at reasoning with him. The rage was back and so vivid, it was almost palpable to Severus, across the room. "You were assaulting another student!" He let out a shaky breath, seeming to calm a little, before visibly turning his attention to the unmoving Ravenclaw. "Are you hurt, Luna?"

She smiled at him. "I'm alright Harry. Just hungry."

This time, Harry's lips twitched into a small smile. "Come on, I think Ron saved you some pudding." He pocketed his wand and dared to approach them unarmed. Even the Potion's Master smirked when the three boys jumped back, out of Harry's way.

Luna pulled out the band from her hair and let the blonde locks fall messily over her shoulder. Then she stepped up beside him and linked his arm. "That's very nice of him," She commented, nonchalant, "I do like pudding."

They started off down the hall, barely missed colliding into Snape under his quick disillusionment charm.

When Luna looked over her shoulder, Severus supposed she could have been giving her attackers one last look. But they were almost out of sight and he would swear by Merlin she was looking directly at him. She gave no indication if she had, as the conversation started up again.

"You missed supper. We were worried." Harry admitted.

"No need, I'm fine."

Harry paused, jerking them both to a stop. He stared at her, shocked. "What? Luna they were bullying you! Terry was hurting you. What part of that was fine?"

Luna shrugged. "The part where you came." She grinned a carefree smile at him.

Harry did not return the smile. His frown deepened. "No, Lu, this is not something you can just brush off. What would have happened if I hadn't gone looking for you? What would they have done to you?"

Luna did not loose the content expression, though it became forced. Harry saw through it. He felt the shudder that ran through her and, if possible, the worried turned frantic. "Luna? What did they say to you?"

"Nothing that matters, Harry."

"It does matter. I don't know why you think it's alright that they pick on you, but it's not. If they - if anyone - so much as looks as you wrong let me or Ron, or even the twins know." When she went to protest Harry cut her off, "I know you can take care of yourself, but trust me, it's nice to have back up. Cowards like Wyles will always have a little gang of morons behind them." He sighed, running his free hand through his disheveled hair. "I have half a mind to tell Snape, at least he'll give them a punishment they deserve. Professor Mcgonagall isn't going to be hard enough on them."

"You'll lose house points."

Harry rolled his eyes. like they had not lost enough already, and it was barely halfway into the first term. "That's down to them."

They reached the halls and entered together, arms still linked. It was relatively empty, barely a dozen students still milling about. At this time of the evening formalities could be thrown aside, so the young Ravenclaw did not hesitate to pull up a seat beside the Weasley's, crossing her legs on the bench and smiling gratefully at Ron when he slid a plate of supper to her, and a second plate filled with treats. Luna went straight for the latter.

Neither of them noticed Snape's seat empty. They would never have suspected the potions master to be at the entrance of the halls, a frown marring his features as he tried to come to terms with what just happened.

He was interrupted from his musings when he heard the distant voices of the boys who had first halted him on his way to dinner. Relinquishing his disillusionment charm, he waited to pounce on them, points and free time deducted at will.