This sits more on the personal preference side, but i don't think saying she's bipolar is quite right. Though i'm not sure how much i should discuss her given that i don't know how far you are into the game, but i can assume it's not very.
The only thing i can say about her is that i don't justify her actions, but i understand where she comes from and why she's like this.
In my personal opinion, she's among the most, if not the most interesting character in the game. But you may have to see for yourself if you want to agree.
Edit: I don't quite understand the part where you keep mentioning that you can't get Bond with her trough repeatable events. You can. I may have forgotten if the choice was unlocked later or not, but it's there. Weekend mornings.