Tenya very quickly fell in love with his new sister. After figuring the more interesting parts of Himiko's quirk out, Tensei remembered he knew a doctor whose quirk created blood. Once Himiko figured out how to copy people's quirks as well as their appearance, she was easily able to keep a continuous supply of her favorite snack.

"Himiko, I need space for the ice cream!" Tensei yelled, looking at a freezer that was mostly full of red packages. In the gym downstairs, Himiko was practicing with her brother's quirk; by the time the two were ready to take the UA exam, she knew Tenya's almost as well as her own. She understood it no more than Katuski, however. Speaking of...

Katsuki was pretty sure patting a cat should not turn one into a ghost in another universe, but here he was, floating above his own drastically changed class. Lots of his classmates looked really different without their quirks. In a world like that, he thought, everyone would be viewed by their own merit. Katsuki was very surprised to find this was not the case. Eight minutes later, Katsuki had finished getting his worldview overturned, and decided he would think about what to do with Deku later. What he didn't know was that travel through the fabric of existence had given him a secondary quirk; every night, he'd travel. At a loss, he followed Izuku's example and got a notebook to detail the four worlds he was interchangeably tossed into; the quirkless world, the one where Deku was a vigilante, the one where he was a villain (and didn't that creep him out to no end) and the one where Deku was a hero. The time period in the other worlds was not consistent; he'd appear before himself as an adult, or a teenager, or his own age, or younger. Katsuki told no one about his nightly adventures; he kept four notebooks, labeled "Quirkless," "Vigilante," "Villain," and "Hero." He didn't let Izuku see them, writing notes on each universe continually. Many things were different, across the four, but there were a few consistencies. One: they always met an Underground hero named Eraserhead. Two: something always happened at a place called USJ. He wasn't clear on what, only that it was bad. Three: something had gone down in Hosu. Deku and two people called Iida and Todoroki were involved. They were, he realized later, the names of two Pro-heroes. Four: there was a forest fire at a summer camp, and people got kidnapped. It changed who, depending on the reality; the villains went after either Deku, Todoroki, some idiot with stupid red hair, or some idiot with stupid purple hair. Four: there was a girl called Eri, and Deku tried to save her. In two realities, he succeeded. In the other two...he didn't. Five: There was a quirk Katsuki was calling "Green Lightning," and it was connected to All Might somehow. In the quirkless universe, it was a magic sword. (Did I mention the quirkless universe had magic? Because it did.)

It took five years before Katsuki found the second part of his informative though unwanted quirk. Exactly five years and a week after that Tuesday, Katsuki fell off a bridge. Eight seconds passed in a place that was gray and empty, and Katsuki ran home, and blood was washed away by rainwater. His reality-traveling quirk had pulled him away from the darknessthatglowedblue, from the womanwithouteyes, from the everlastingandunbrokenpillarsoftimethatheraldedtheend.

Immortality quirks were very rare; as a secondary aspect of another, unheard of; as a second quirk, nonexistent. The day after, Katsuki went to the library, to read up on quirks, and maybe get an explanation.

Hitoshi was having a good day. Two years ago, with Dabi's help, he'd gotten his previous foster parents arrested. Now, he lived with the heroes Eraserhead and Present Mic. He hadn't told his friend that part. At the moment, he was looking for evidence of people getting randomly bodyswapped on a particular day. If he could find Dabi's brother, he could find Dabi. Carrying his books to a table, he slammed them down, not noticing the table's other occupant.

"@ *@*!" said other occupant shouted. He had blond, spiky hair, red eyes, and a notebook and library book open before him.

Katsuki, finding nothing that could help, had started copying some runes from memory into his notebook, with the help of a historical textbook. Maybe he could figure magic out. Unfortunately, the spells didn't seem to be working. Someone dropped a pile of books on the table, and Katsuki looked up, cursing, before he cut off in shock. Before him stood the purple-haired idiot. In the reality he'd gotten kidnapped, he'd managed to reach the Heroics course of UA; in the other three, he'd been in General Education. Katsuki glared at the boy, noticing a chat app open on his phone. He was texting someone named Dabi. Where had he heard the name before? Katsuki went back to figuring runes out, ignoring the other table's other occupant. Dabi, where had he heard that?

Hitoshi watched the other boy scribble in his book.

"Hi. I'm Shinsou." he said, holding out his hand.

"Did I ask?" the other grumbled.

"It's too bad, really. I did a project on celtic runes last year, I might be able to help you out." he said. The other boy looked up, and handed Hitoshi his notebook, pointing at a line of symbols.

"What's this mean, then?" he asked.

"It looks like you're trying to say [divine the other's uniqueness]. What this really says is [divide the over's unicorn]. You're mispelling everything, the lines work like -this-." Hitoshi said, scribbling a correction.

"If only it was known how to pronounce them." Hitoshi mused. The boy glared at the notebook, muttered something, then looked at Hitoshi oddly.

"What are you looking at?" Hitoshi asked.

"Nothing. What's your quirk?" the other asked.

"I'm not going to tell you that, you haven't even told me your name." Hitoshi said. The nerve of some people.

"I'm Bakugou. My quirk's Explosions. Yours?" Hmph. Telling someone his quirk was a good way to lose friends, but this guy was rude, so who cared.

"Brainwashing. I can control people I talk to," Hitoshi said, waiting for the reaction.

"It worked. It actually [bleeping] worked! Suck it, magical quirkless alternate!" Bakugou grinned, writing in his notebook. Hitoshi gained the impression Bakugou was not talking to him.

"Wait...HalfnHalf's brother! I knew I knew that name. See you later, Runes!" Bakugou ran out of the library. Hitoshi stared after him, feeling as though he had just encountered a cryptid.

Katsuki had figured out magic. He had actually figured out magic. He could see impressions of other's quirks, with this spell. In the other world, it was used to view magical proficiencies, but after seeing glowing ropes floating from Shinsou's mouth to wrap around his head, he'd assumed it was some sort of verbal mind control, which it had turned out to be. Katsuki was going to be the number one hero in every reality, and no one could stop him.

Notes:

Katsuki! Has! Magic! Powers! (and all his swears are censored out) I just thought that there were so many cool fics in which Izuku has dimension travel/immortality and decided Katsuki should have a turn. I Really Do Not Like Canon Katsuki (at least before his redemption arc). So I fixed him.

Next chapter: Shouto and Zuko are both very confused, and Fuyumi does her best