Izuku stood before the psychotic doctor and wasn't sure what to do or say when his father walked into the room.
"It's good to see you up and about. Your ability to rebound is truly impressive. The only person I've met that was able to take on so many new quirks without dying was Gigantomachia, and even then not so quickly. I know that it still took a toll on you, so today's activities won't be physically demanding."
He started to walk away and waved for Izuku to follow.
At first Izuku was going to stand his ground and defy him even in these small insignificant ways, but he found himself following anyway. There really wasn't anything to gain by fighting him all the time. Even if it meant swallowing his pride, he needed to choose his battles and just do what he was told for now.
He could have sworn he caught a vicious grin on the man's face for a fraction of a second, but it was gone just quick as it appeared. He suddenly vomited out some sort of black goo and found himself standing in a new location, but it seemed like it was still underground. The fact that his father had access to at least two warping quirks was deeply concerning, but there was nothing to be done about it. Izuku just kept stumbling forward, having difficulty keeping up since the IV stand had been left behind, so he couldn't use it to support himself.
"Now, I'm sure you've been wondering what happened to your classmates that had been captured along with you. Personally, I didn't care one way or the other, I had simply told Overhaul to bring me my children, where to find them, and then gave him access to a few Nomu to make it easier. However, I can respect the efficiency and initiative that he has, so I've given him a go ahead for his current plan for them. Well, we can go over that later, there's a task I have for you before we start deciding what to do with your little friends."
They moved through a few security doors, getting even deeper into the compound. Eventually they came to an observation deck of sorts, with a mirror in front of them that was currently opaque.
"Consider this another test. You already passed my test of your quirk's endurance, now I want to test your mind and your ability to analyze. Now, before we begin, let me warn you away from doing anything foolish. If you make any attempt at freeing the other students, I will fill their room with poison gas and let them all die. Am I understood?"
Izuku just nodded, not wanting to put his friends at risk. The full wall mirror suddenly became transparent, allowing him to look down into the large open room with the entirety of classes 1A and 1B in cages with a handful of armed guards patrolling the room. They all wore variations of the same gray jumpsuit and most had some level of injury visible. Izuku struggled to remain calm and not strike out at his father for harming the people he loved since he knew it would only make things worse.
"The game I have is a simple one. One of the people down there was my spy that I used to keep an eye on the school. I want you to figure out who it is. You can enter the room and ask them whatever questions you want, but try to stay on topic, you only have a limited amount of time to find the answer."
"How much time do I have?"
"Hm… how about an hour?"
Izuku and Tanaka both gave a quiet and panicked cry of "An hour?!" under their breath
"You're right, that's much too long. Half an hour is more than enough." He pulled a pocket watch out of his vest and tapped the button on the top. "If you fail to discover the truth before the time is up then you will never see your friends again. Your time has already started, so I'd suggest getting a move on."
In retrospect, the door to his left probably would have led him down into the room below, but he didn't have the patience for that. He took a few stumbling steps forward before throwing his body through the two way mirror with all the strength he had left. He landed on the floor in a shower of glass and a loud cracking noise as the cement floor broke under the force of his now steel bones colliding with it.
He slowly got to his feet, leaning heavily against the wall. The handful of guards looked over in alarm and were prepared to attack when his father's voice carried throughout the room
"You may leave your posts, I will be keeping this location secure for the moment."
The guards looked over at the overhead viewing area, seeing his father through the now open space. The guards left quickly, not wanting to be anywhere that All For One also was. They worked for him, but clearly feared him more than anything else and were more than happy to follow the order of getting as far away as possible from their supervillain boss.
He heard a groggy and weak voice from his left. "Izuku? Is that you?"
He looked over and saw Shoji, who had a black eye along with other bruises and seemed to have a hard time focusing on him. Izuku immediately went over to him and struggled to hold back tears. "Yeah, I'm here, I'm here now. Are you okay, what happened to you?"
"I'm… uh…"
Mina was in the cage next to him and spoke up. "He was hit with a tranquilizer dart a few minutes ago for trying to break the lock, he should be fine once it wears off. How are you here though, who was that guy who told the guards to leave?"
He heard Tokoyami's voice from not much further down, under a series of very bright lights that were shining down on him and the pitch black student from 1-B to keep them weak. "Are you here to rescue us from this banquet of madness?"
He looked around and saw his other classmates looking at him with the same mix of hope and suspicion.
"I- I really want to get you all out of here, but I can't save you, not yet anyways." A few started to speak up at that but he cut them off. "I know you have a ton of questions, but I'm on a very strict time limit right now so I'm going to give you the very short version of the story and hopefully I can tell you the rest later."
He took a deep breath and spoke as quickly as possible without being hard to understand. "My dad is the supervillain in charge here, I only found out about him recently, but he's really bad and can give and take quirks. He's the real puppet master behind the League of Villains, so yeah, very evil stuff and a big fan of murdering heroes. I don't really know what is going on, but after not hearing from him for over a decade he came back and decided he wants me as his successor, so he kidnapped me and all his other children. I have like a dozen or two half siblings. Um, I don't know what he plans to do with you all, it seems like you were all secondary targets but I have a feeling it's still going to be bad. As a test for if I'm a good possible successor he told me to find out which of you all is the spy that works for him in the next half hour with it implied he'll kill you all if I can't."
Izuku nearly gasped for air after getting all that out. His classmates were all struck into silence at the information dump they just received. His entire body was trembling as he tried to maintain his composure.
After a few moments he heard a ribbit from behind him. "Kero, what do you need from us?"
"I need you to share whatever you know, any suspicions or strange behavior that didn't add up. Was there anyone that you had doubts about already? I know it's unpleasant to accuse our classmates, but right now it's that or die."
The silence was deafening, until the first person started them off. He didn't know the girl well, but he knew she was from 1-B. "Well… Monoma was with us in the dorms when we were ambushed, but he isn't here with the rest of us."
The moment she had finished, a flood of accusations and defenses followed. Everyone was terrified of being called the traitor and it didn't take a genius to guess what would happen to the one he picked. For his part, Izuku closed his eyes and just listened to all the information coming at him as he tried to piece it together.
"Shishida keeps going on long walks and no one knows where he goes." "I just like walking in the forest area at night!"
"Shinso wasn't at the dorm before we all got captured, so how'd he get caught like we did?" (Shinso's response was muffled by the muzzle he'd been put in.)
"No one knows anything about Bondo's family or his life outside of school." "It's not a secret! You just didn't ask. I'll tell you anything."
"I saw Mina trying to break into Aizawa's office last week." "I just wanted to get a peek at the exam questions!"
How could he determine who had been genuine all year and who had been lying? Could he even be positive it wasn't one of his closest friends?
Tanaka's voice in his ear answered his mumbled question. "You can't. I know you're big on feelings, but you can't right now. Don't rely on their personalities, anyone can lie about who they are, or actually be good but have a family member taken hostage. Treat it like a quirk you're taking apart, just use the facts and figure out who it can't be."
Right. Just like any other analysis. Take the information he has and rule out options. That's how you solve any logic puzzle.
"Please be quiet for a second, I need to check something." The room got silent again, no one wanted to interrupt the person who was deciding their fate. He turned to face his father, making sure to keep his composure and not give into the rage and despair he felt when looking at him.
"Is Shouto actually dead, or was it faked and he's a part of your organization?"
The man responded with booming laughter. "That's the kind of thinking I like. Don't trust anyone, even corpses. I'll be nice and let you know that the young Todoroki was never in my employ, but we didn't kill him either. In fact, we had nothing to do with that entire scandal, it was all faked. I suppose that's a puzzle for another day."
Izuku nodded and felt a strong sense of relief.
"Oh, now that's fascinating. You already knew that. Don't look so shocked, you can't rule an evil organization for over a hundred years without becoming very good at reading people. The real question here is why you would ask a question you knew the answer to, and why my answer made you relax slightly."
The man tapped his chin in thought.
"It wasn't out of concern for your friend and making sure I didn't know where he was. No, you wouldn't look into that while on the clock to save your other friends… Ah, I see, some of your little friends down there know the truth about him, so my lack of knowledge cleared their names. Very clever indeed, please continue."
Izuku turned back around to look at his classmates. His father was right, his answer had proved the innocence of Jiro, Shoji, Tokoyami, and Yaoyorozu.
But that still left most of 1-A and all of 1-B, he needed a way to narrow things down way more and fast. He went over the information he had over and over trying to piece things together.
He suddenly came to a stop and moved further down the row of cages to stand in front of Shinso. He probably should have asked before doing something so rash, but he couldn't bring himself to be cautious anymore. Izuku ripped the door off the metal cage and stepped up to a very frightened Shinso who was shaking his head and backing up as far as he could.
With a quick movement he ripped the muzzle in half. "Sorry, I could have done that better, but I have a very important question for you. Did you tell anyone outside of 1-A that you did extra training with Aizawa and Suzuki?"
He shook his head rapidly, his voice raspy and weak. "No, I don't really interact with anyone outside of 1-A. Please, I didn't do it. I'm not a villain, I swear."
He gave him a soft smile. "I know, I don't think you'd ever be a villain." But that was the problem. He didn't think any of his classmates were capable of villainy.
Izuku stepped out of Shinso's cage and started thinking out loud, partly to explain his thoughts to his classmates so they knew what was going on.
"The targets of the attack on UA were myself, Suzuki, and Monoma. And since Shinso is here that means they got Suzuki as well. But it's not exactly common knowledge of where the two of them train, it just wasn't interesting enough to be shared around. So I really need to know, did anyone in class A talk to anyone outside the class about Suzuki's training schedule? Even just an offhand comment in passing?"
Everyone was quiet and shook their heads. Shinso spoke up, barely above a whisper. "We weren't scheduled that day. He just said something about not being lazy and always being prepared, which is pretty normal for him. So, even if someone looked at his schedule they wouldn't have known the time even though it was at the regular spot of Gym Gamma."
Izuku nodded. "That narrows it down a lot. The traitor couldn't be anyone who wasn't there to see them leave for training and notice they weren't in the dorms. Which means the traitor has to be someone from 1-A."
He heard a chorus of relieved sighs from the 1-B students mixed with the alarmed gasps from 1-A.
From when 1-A had started the year, they'd lost 7 classmates and gained two. Bakugo had been arrested. Iida was arrested and then killed. Shouto ran away. Uraraka, Koda, Sato, and Aoyama transferred out. Then two more were added with Shinso and Suzuki.
With his closest friends cleared, that meant the remaining suspects were Mina, Tsuyu, Ojiro, Kaminari, Kirishima, Sero, Mineta, Shinso, and Hagakure.
He started running through every interaction he'd had with them. Even with narrowing it down so much it was still too many options. Was there anyone else he could rule out? Were any of them more suspicious than another? Some of them had quirks that were better for spying, did that make them more suspect?
He was running out of time and needed to make a choice but was terrified of being wrong, hell, he wasn't even sure he wanted to be right. He wanted it to be a trick question where none of his classmates had betrayed him and everyone else.
"Well son, do you have your answer?"
Here we are, another exciting moment I've had planned for a long time. I would love to know who you think the traitor is, obviously it's not the same as canon.
As always, I love to hear your thoughts and questions.