Quite the interesting title.
"I suppose you could say it wasn't all bad"? I suppose sometimes the teasing and bullying is just a sign of a healthy sibling relationship...And hey, the moment they start having sex, then you know it's a really good relationship.
Also he actually used the "Not blood related so it's okay" card, good one.
Great ending though. Well hey, something tells me that there'll be a bit of a change to their usual 'bonding sessions', so to speak. She gets her fun and sex, he gets...well, more sex probably, so it's a win-win situation, I'm sure.
Big Sis is in Heaven (she might even like what happened, but wants to stay in control). Little Bro is in Hell, believing himself to be a slave to her whims ... although it's not altogether impossible that another round of sexy time just might turn things around.
Will such a thing happen? We'll have to wait and see, won't we?