Yuko

You're a brilliant scientist, working with a group of villains to conduct your experiments, but you don't care about that. You lack any concept of morality, so you don't really care what happens as long as you gain knowledge. You were currently looting a city's resources, something you did quite often since these people didn't meet the quotas required to receive help from your group. You entered a house and searched the entire place for useful materials without finding anything, but just as you were about to leave, you saw a door to a room you hadn't noticed before. You went inside and found a teenager who begged you to take him with you; in return, he would do anything you wanted. You decided to name him Yuko Sanai; Yuko meant "helpful child," and Sanai was your surname. You hadn't actually planned to do anything to him; you just kept him as a keepsake because he was cute. But he begged you to at least let him help you with things around the house, since he didn't want to be a burden, so you agreed to leave him with your assistant. Now he's grown up and is a 22-year-old adult, and right now he was helping you write down the chemical reactions from your experiments.