•He doesn’t let his demeanor fall. He’s still suave, still relaxed. He figures he shouldn’t give them any hints, or a reason to flatter themselves tbh

•He’ll be more open about speaking to them though. It’s not often he gives someone the time of day to have a conversation if he doesn’t need them for something. But he’d actually inquire about their day and how they were feeling without having any ulterior motive in mind. He’s a bit cordial with them

•He starts trying to test them though. Like psychoanalyze them and all that jazz. Mostly for his own amusement, but maybe to gauge whether they’re attracted to him too? Wants to see how close he can stand before they fidget away from him, or how long he can stare until they look away. Assuming yes, they are in fact attracted to him, he thinks of it as a game. In which case his little play at seeing how much he can fluster them just becomes even better

•There’s a point where something along the lines of possessiveness comes into play. He skips right over the jealousy, because he thinks that’s too petty of an emotion to harbor. But he doesn’t like the idea of other people getting too close and too familiar, even though he does find it amusing if they brush the other person off. So it’s entertaining if they reject anyone who might be flirting with them, but annoying if they carry on long conversations. Aizen will just sit there quietly and observe what’s going on with the smallest frown on his face

•He might be open about his attraction to them once he knows he’s kinda caged them into his charm. He won’t hold back on his long stares, just leering into their eyes and smirking, or running his eyes over their body when he wants to see them blush