THIS IS A VERY GOOD QUESTION ISN'T IT.

I could see Jeane being pretty close to both of her bros, honestly, since the shitstorm that is their canon family isn't factor yet. She'd probably side more with Henry when Travis is doing something dumb to make him feel stupid, but secretly join him (or even enable him) every now and again because she's a shit.

Also if I go with her being the youngest like in canon I want them to constantly tease her about that.