Disclaimer: I do not own DC Comics or Harry Potter.

This fic is an AU and not compliant with books 6&7.

Impulse Control

A DC Comics/Harry Potter crossover

oOo

For the first time in his career, Severus Snape was actually looking forward to the upcoming school year. Voldemort was dead, for good this time. Albus had finally consented to give him the DADA position. And best of all, Harry Potter was no longer at Hogwarts. Last year had been his seventh and final year.

Severus was a free man. Finally.

He still had to deal with the Weaselette and the Lovegood girl, but that he could handle—as long as Potter stayed out of the picture.

In fact, he was in such a good mood that he actually felt like smiling. Of course, that simply wouldn't do. He had worked long and hard to cultivate his reputation as the meanest professor at Hogwarts and he wasn't about to ruin it now. As long as the students feared him, they would be on their best behavior. It might not be the best teaching method, but it worked for him just fine. He allowed himself a small, decidedly wicked smirk as the doors of the Great Hall opened and the first years crept in.

He scanned the crowd of tiny witches and wizards, trying to mentally sort them into houses by their reactions. Blonde girl with pigtails? Hufflepuff. Perfectly knotted tie and smirk? Soon to be one his snakes. If he wasn't mistaken, that one was a distant relative of McGonagall. Probably a Gryff then. Most of her clan ended up there. His eyes passed over the students, grouping them into this house or that, until they settled on one odd-looking boy and a chill ran down his spine.

Where in Merlin's name did that come from? The boy that caused the odd reaction was smaller and slimmer than most of his yearmates, but seemed to be in good health. With his rumpled robes and brown hair in disarray, he had a windswept look about him. But the most amazing thing about the child was that—in a group of scared, nervous, and awed firsties—the boy looked bored. Not even the Sorting Hat's song fazed him. His golden eyes gazed at nothing in particular as his abnormally large feet tapped out an impatient rhythm.

Severus blinked, then stared hard at the foot that peeked out from the hem of the child's robes. For a brief moment, it had seemed that the boy's trainer was tapping so fast that it became blurry, like the shimmer of a badly cast glamour charm. Taking a second look, he decided that it was merely his eyes playing tricks on him. Or at least he hoped so, as he had no other explanation.

Something about the child made Severus uneasy and he found himself unable to tear his attention away when McGonagall stood and began calling names.

"Bart Allen."

Severus raised a surprised eyebrow as the boy jerked into action, sprinting across the hall and hopping onto the stool, smashing the hat down on his head. All eyes focused on the child, growing more and more impatient as the sorting dragged on. At the seven minute mark, the students breathed a collective sigh of relief as the hat opened its mouth—

—and retched. It spasmed once, then whimpered. Turning to McGonagall, it pleaded with her, its voice pained: "Please. So many thoughts…so fast…can't focus…help."

The stunned Transfiguration professor moved forward, yanking the hat off the boy's head. It went limp in her hands. Unsure how to proceed, McGonagall looked to the Headmaster, but he merely shrugged.

The hat's voice was so weak that the stunned audience almost missed the whispered "Gryffindor."

The boy grinned happily at the abused headgear and sprinted to the table of tentatively clapping red and gold clad students. He didn't seem to notice that they gave him a wide berth as he settled amongst them on the bench.

As Severus watched McGonagall and Dumbledore attempt to convince the frazzled hat to finish the sorting, unease settled heavily in his stomach, making him nauseous. His hand twitched nervously in the direction of his wand and his instincts were screaming at him to run, but he maintained his calm façade. Inwardly, his mind was racing as he mentally composed a letter asking Dumbledore for time off, maybe a year or seven, for independent research in the Amazon rainforests.

oOo

Author's Note: Speedsters + Magic = OMGWTF TAKE COVER

I imagine that might be almost as dangerous as speedsters and caffeine.

This has been yet another silly little crossover one-shot, conceived and written in less than an hour. Thanks for reading!