nothing too set in stone! just that he was jealous when she was born, typical older child thing, he picked on her from then until now but not in a nasty way. their parents died when she was 15 and they were sent off to live with their aunt in london (they were born and raised in dublin, ireland) at that point he would've been probably old enough to be on his own, so you could definitely have freedom with that part! but other than that, they're close but not annoyingly so!