Shouto Todoroki had friends for the very first time in his life. According to his highly reliable online sources, friends pranked friends on April Fool's Day. Alas, Shouto's first attempt at a prank had been a flop. He'd dyed his hair to swap the red and white halves, but no one had even noticed.

This time, Shouto had planned the best prank ever. He'd spent hours of research coming up with fake conspiracy theories about how every single member of his class was related to a villain. Shouto had already gotten three of his classmates alone and given them a spiel about which villain they were related to: Kirishima to Gigantomachia, Hitoshi to Dictator, and Fumikage to Thief Takami. Thanks to Shouto's natural deadpan face, they'd believed that he believed his fake theories. Fumikage in particular had been in desperate denial before Shouto revealed the prank.

Shouto hadn't been able to think of a good villain for Aoyama, so instead he'd created a fake theory that Aoyama was a spy for the League of Villains. However, Aoyama had gone so pale that Shouto had quickly said "April Fool's!" before he'd even given half his evidence. Then they'd both laughed, Aoyama a tad hysterically.

Shouto's next target would be Izuku Midoriya. Shouto had created the perfect theory for his best friend and a manilla folder full of evidence. This would be so much fun! Shouto texted Izuku asking to meet in an empty classroom.

Minutes later, Izuku stepped into the classroom. "Is this about your All Might love child theory again?"

Shouto shook his head. "No, I've finally realized that I was wrong about All Might being your father."

Izuku startled. "Really?"

"Yes, because I realized that your father is All for One."

Izuku choked. "U-uh, that's, uh, a bit far-fetched, don't you think?" His face turned bright red.

Hook, line, and sinker! Izuku had completely bought it! Shouto kept his face straight through an act of willpower. Solemnly, he said, "I have an entire folder of evidence. I know this must come as a shock, but I thought you had to right to know."

"I'd rather you go back to telling people that All Might is my father." Izuku pulled over a desk and sat down. "Let's nip this in the bud. I'm sure everything you've found can be easily explained away."

The victim had been drawn into a debate. Perfect. Shouto opened up his folder. "I first became suspicious when All for One ignored that tiny wall we were hidden behind at Kamino."

"Ignored? I thought he didn't see us."

"When he has X-Ray and Search? Unlikely. He deliberately didn't attack us."

Izuku raised an eyebrow. "Why pin that on me? All for One could be Tenya Iida's father according to your theory. See how silly that sounds?"

"The Iida family is well-known. Your father lives in America and has never once returned despite all the chaotic events in your life lately. Very suspicious."

Izuku sighed. "There are a lot of people who work abroad. A lot of absentee fathers in the world, too."

"Then at Kamino, we heard All for One say that All Might took something from him." Shouto pointed. "Took his son!"

Izuku crossed his arms. "You're reaching like an Olympic gymnast. Honestly, so far everything you've said could apply to All for One being the father of Tenya Iida, or you for that matter."

Shouto was tempted to mention All for One mumbling about quirks at Kamino, but he'd noticed that Izuku acted overly apologetic about his mumbling habit. What if he'd been criticized for it in the past? In case it was a sore spot, Shouto decided not to bring it up. Pranks were supposed to be fun for everyone involved. For the same reason, he did not mention Izuku's fragile body and former quirklessness either, even though both would have made great fake evidence of him having a father from the dawn of the age of quirks. Instead, Shouto said, "Then there was the notorious incident when Tomura called you 'little brother'—"

Izuku yelped, "It wasn't notorious! Tomura was possessed and confused!"

"All for One also went easy on you during that fight. I would swear that Gigantomachia seemed to be looking for you."

"It only seemed that way because I was in the same area as Tomura."

"You can use multiple quirks."

Izuku sighed. "I explained to you where the quirks came from. Inside One for All."

"Yes, but why have none of the other users ever activated the quirks before? What if you have a body that can handle multiple quirks?"

"Or what if it's evidence of quirk singularity?" Izuku countered.

Shouto grinned, proud that he'd pushed Izuku far enough to get him reaching for conspiracy theories too. "There's a certain physical resemblance between you two. Your hands look similar. I've also noticed some similar gestures, listed in Appendix A of the 'Physical Appearance' file."

Izuku made no move toward the file. He snorted. "I look like a guy with no face? Should I be insulted?"

Although Izuku's tone had been joking, Shouto didn't want to risk accidentally causing offense. He changed the subject. "I haven't dropped my favorite piece of evidence."

Izuku gestured. "Go on."

"All for One's helmet is clearly based off Darth Vader's! He's pulling a long 'I am your father' reference."

Izuku pinched the bridge of his nose. "Are you sure you don't want to go back to the All Might lovechild theory? I have to go, it's almost time for class."

"Wait! What about this?" Shouto pulled out a file. "Pictures of your childhood pediatrician Dr. Tsubasa, who looks uncannily like the villainous Dr. Ujiko."

Izuku flipped through the pages. "Whoa, they're seriously the same person. It's been so long since I've seen the man, I never noticed. I should bring this to Nezu's attention. It's probably an old alias, but we might be able to use it. Thank you." He pocketed the file. "But I don't see what this has to do with my father."

Shouto said, "Obviously your father sent his mad scientist to check to see if you'd inherited his quirk."

Izuku said, "If Dr. Tsubasa was working for All for One, then he was probably checking all the children's quirks for their usefulness and easy of stealing. Not mine in particular. Phew, I got lucky there." His face paled. "I wonder if he went after any of my other childhood friends? I need to look into this." Izuku started to rise.

Shouto grabbed his wrist. "Just one more piece of evidence. Please. I worked so hard on this." He worried he might have given himself away with that last line, but he couldn't let the prank end without revealing his ace.

Izuku sat down. "Fine, but this had better not be more nonsense about Star Wars."

"Ta-da!" Shouto pulled out a faded copy of a news article from the dawn of the age of quirks. "This is the only surviving mention of All for One's past that I could find in existence. Look at his picture." Shouto pointed at the curly-haired man wearing a suit. "He could be your older brother with white hair…or your father."

Izuku stared at the ancient photo. His mouth opened and closed. His hands shook. He did not seem able to speak.

This reaction worried Shouto. Maybe he'd gone a little too far. If Izuku was starting to get upset, then it was time to pull the plug on the prank. "Happy April Fool's Day! Just kidding, I know your dad is All Might."

Izuku burst out laughing. "You really had me going there." He collapsed back into the chair, smiling. "What an elaborate prank! It must have taken you ages to put together all that fake information."

Shouto beamed, pleased to have pulled off a successful April Fool's prank. "Thank you. I worked very hard on it. I have theories prepared for every single member of our class being related to a villain. Please don't tell anyone about the joke until I've had time to talk to all of them."

Izuku chuckled. "It will be fun to see the looks on their faces. Where did you find a picture of my father to photoshop into that old news article?"

Shouto said, "I didn't photoshop anything. That's a picture of All for One when he was young. I thought the resemblance was a funny coincidence." He wondered why his friend abruptly stopped laughing.


Author's Note: Happy Late April Fool's Day! I wish I'd posted this on April 1, but I hadn't even thought up the idea yet. Then I didn't feel like waiting a full year.

All the conspiracy theories that Shouto made up to prank his friends turned out to be true in this AU. All the theories that he actually believes are wrong. Shouto trying to prank his class by swapping the colors of his hair comes from BNHA smash:
aimportantdragoncollector.
tumblr.
com/
post/683445491605946368/catboy-todoroki-happy-april-fools-day-to-only

Please, Horikoshi, drop a Dad for One reveal exactly like this. And do it in an omake so no one knows if you're serious or not.