yes yes yes yes oh my god <3
what originally draws her to him is his orb, specifically the moment he got on his knees and let her feel it. she was neutral on him before then, but something about his openness about his own "monstrosity" just. grabbed her. they're both drawn to power not out of a need for domination, but because both of them have a fear of inadequacy. senna was literally born to be bhaal's favorite, to live up to be a world destroyer, and throughout her life she was constantly trying to match these seemingly impossible standards she was created for.
gale is a certified yapper and senna doesn't really like to talk. she's more of an observer. she keeps all of her thoughts in her journals. at first gale thinks she doesn't care about what he has to say, but when she eventually shows him her journal, he realizes she's been cataloging literally everything he says. he thinks its incredibly endearing (though he has a hard time reading it because her handwriting is. not great) (she has a few pages dedicated to every one of her companions with little doodles at the top that fit them. gale has little lightning bolts and a recreation of the mark on his chest)
during act 1 when senna is so amnesia ridden and fucked up that she's practically navigating everything like a newborn again, she especially loved to probe his brain. he seemed so knowledgeable about everything that he was the first person she went to when she really didn't understand what was going on or what something was. + more stuff for her journals!!
gale is so... romantic and gentle with her. and she's never experienced kindness or gentleness at all. her childhood and entire life was very rough and mean, so the way he treats her is incredibly jarring. at first she wants to run away from it, but she realizes its something that she really craves. love & affection for her has always been something incredibly carnal, she really loves with her teeth. (speaking of which. she's constantly gnawing on gale like a chew toy. especially during sex. after he looks like he's been attacked. just covered in bruises & teeth marks)
at first she's keen on him taking the crown of karsus as a "fuck you" to mystra but when she sees how... corrupted it would make him, and how already corrupted by his own ambition he gets, it reminds her too much of gortash and she hates it. she gives him the silent treatment and leaves him at camp for a few days while she has to take time to really think about it. it ends up boiling over in a huge argument that ends with them fucking & pouring their hearts out to each other. gale doesn't take the crown of karsus. lmao.
senna is absolutely more of the "silent until angry, then absolutely loses her shit" type and it really really comes out with gale. (when i was watching mickey 17... nasha's anger when it comes to mickey is soooo similar to senna with gale) she has almost gotten him fired on multiple occasions at blackstaff after yelling at his coworkers when they're even slightly mean to him
n e ways i love them i love them..