Aizen has largely shown no particular care for anyone. Those he has claimed or assumed to have feelings for him have been betrayed. He has shown amusement toward Gin and has no shown no feelings either way about Tosen. Aizen said that he always thought of Gin as his subordinate though this does not mean he cares for him. Aizen needed help to formulate his plan some helped knowingly some unknowingly, Aizen was able to influence Gin from a young age and values him as an asset but no more than that.