A/N: This fic does deal with themes of depression, although not too severely or in-depth.

Sherlock, where's Sherlock? John turned in a full circle, scanning the room for the familiar form in black. When he didn't see it, he took off running through the closest set of doors. "Sherlock!" he shouted, before a hand clapped itself over his mouth and pulled him behind one of the tapestries.

John kicked backwards as he lunged forward, away from the arms that had encircled his waist. He managed to land a blow and his captor grunted in pain, loosening their grip slightly. "John," a voice hissed in his ear. "John, stop!"

"Sherlock?" John relaxed immediately and turned around, recognizing the person who was holding him so tightly. "Are you out of your bloody mind? There are Dementors out; what are you doing?"

"Saving you," Sherlock said shortly. Letting go of John, he reached into his pocket and drew his wand, casting a small Lumos. In the soft light, his face was sharp, the skin across his cheekbones pulled tighter than ever.

John huffed a laugh incredulously. "Saving me?" He shook his head. "You're going to get killed – they won't care that Mycroft's a pureblood – "

"Shut up," Sherlock ordered, extinguishing the light with a flick of his wand.

John went immediately silent, recognizing the sound an instant after Sherlock spoke. The rattling noise of a Dementor echoed down the hallway, drifting ever closer to their hiding spot, bringing its awful aura with it.

It was a feeling John never got used to no matter how much he felt it. Just give up, a voice inside his mind whispered. Why fight it? It's a losing battle. Numbness settled over him, a crushing weight that filled his lungs and left him struggling to breathe.

Beside him, Sherlock grasped his wand tightly, muttering to himself. John recognized the words as the charm they'd been learning in Defense, the one to summon their Patronus, but he couldn't bring himself to care as the sound of the Dementor's rattling breath came closer.

"Ex - expecto – expec – " Sherlock whispered and then his breath hitched and he stopped talking.

Through the dull emptiness that had surrounded his senses, John noticed Sherlock drop his hand and tuck his wand into his pocket. He let out a tiny breath and then, moving like a sleepwalker, he twitched aside the curtain and stepped out into the hallway.

"No," John choked out, his voice hollow even to his own ears, as the Dementor turned its empty hood towards Sherlock and glided closer to him across the stones.

"It'll make it right," Sherlock muttered and the resignation and finality in his voice went straight through to John's heart.

"No," John said, the weight of everything he was trying to feel and couldn't poured into the words. Drawing his wand, he levelled it at the Dementor that was looming over Sherlock. "Expecto Patronum."

Closing his eyes, he refused to think of the fear, the terror, of anything but his fierce need for Sherlock to survive, the wild hope that both of them would survive and make it out of the hellscape their lives had become. He remembered the moment they had shared on top of the Astronomy Tower, the night Sherlock had rolled up his sleeve and trusted him, and a hundred other moments that he threw at the Dementor, at anything that would take Sherlock from him. "Expecto Patronum!" he shouted again and the wisp of light that surrounded him shaped itself into an animal and hurtled toward Sherlock.

The Dementor shrieked and fled, disappearing as it if it had never been there, and Sherlock blinked. "John?" he said hoarsely, looking around.

"Yeah," John said, taking a step forwards. "Yeah, I'm here."

Sherlock attempted to smile and then he lurched forward shakily into John's arms. "John," he whispered again, like he was trying to convince himself he was here, standing in the corridor, not getting his soul sucked out.

"It's all right," John said, although nothing was really all right these days and this least of all. "Here, let's – let's sit down," he whispered as Sherlock crumpled into him and he guided both of them to the floor.

Why had Sherlock walked towards the Dementor? Why had he left the Great Hall at all? John pushed down the questions rising in his mind, resolving to ask them later as Sherlock shuddered again in his arms.

"It's all right," he murmured again, carding his fingers through Sherlock's hair, not sure which one of them he was saying it to.

Relaxing slightly into John's shoulder, Sherlock whispered, "Could you do it again?" so quietly he could hardly hear.

Taking his wand out of his pocket John gently moved it through the air and let the comfort of the moment flow through him. "Expecto Patronum," and there it was dancing through the air – a hedgehog that alighted onto Sherlock's lap and nuzzled into his robes.

"It likes me," Sherlock said incredulously, turning to look at John.

John curled closer to Sherlock, covering one of the Ravenclaw's still-trembling hands with his own. "Of course it does," he said softly. "How could it not?"

Sherlock laughed bitterly, his body stiffening. "John," he began, his eyes hardening.

"No," John said firmly, talking over whatever Sherlock had been about to say. "I don't care, Sherlock. I don't care about what Donovan and Anderson have to say, or the war, or even the bloody Dark Lord himself. I care about you."

Sherlock huffed as John's patronus snuggled closer. "You're in danger," he insisted softly.

"In case you haven't noticed," John replied, "there's a war going on. And," he went on, "even if there wasn't, I'd still be here." He grabbed Sherlock's wrist to stop him from getting up. "Look," he said, "I didn't leave on top of the Astronomy Tower and I am not leaving now."

Sherlock settled back on the floor, one hand trembling slightly as he ran a hand over John's patronus. "Why?" he asked softly.

There were too many answers to that question, and John knew Sherlock knew several of them better than he did himself. Finally, he let out a long breath. "I guess it's," because I love you, because I care about you, because I can't imagine Hogwarts without you, "just because."