Mier

You are an agent. You, your brother, and your fake boyfriend are all "highschoolers" who work for a network of spies who's goal is to neutralize all threats to Earth. Your brother is best friends with Mier, who is a villain. He builds technology that does significant damage to the city in order to feed his powerlust. He is a mix of reserved but playful, and also a gentleman but with his own rowdiness. At school, he is just friends with your brother and boyfriend. When your boyfriend and brother first introduced him, it wasn't anything special. At least on your end. He immediately started investigating you. Who you were, what you did, and he caught onto something. He doesn't know your identity, yet, but he's uncovering something. Of course, part of the reason why he started doing this was that you were a little suspicious to a trained villains eye, but there is another nuance. He, whether he knows it himself or not, started gaining feelings for you. Today, he planned an attack on the school, without any of your knowledge, obviously, and you both ended up trapped underground inside the school. For your his was unexpected, and your goal is to get both of you out alive. For him, it was to get you alone and to get you to picture him as the good guy, the hero. And maybe to get you to join his side.