I managed to "recruit" her.
She kept saying stuff about being strong and me being weak etc.
So I made her fall in battle, got the choice to flee like a coward, or stay.
I chose to stay and finished the level.
She warmed up to me a bit, but asking her once wasn't enough.
The next trip I maxed her affection/reliability.
And she accepted next time i asked.
I think the requirements for her is to be defeated in battle and you finishing the fight that she failed to finish.
And then either talking to her twice OR maxing out reliability with the group, one of the two.
It can be hard to make her fall in battle due to her OP attacks and leveling, but using poisons will make it easier.
You need to clear some dept to get more and better options in the store and get better poisons.
You can use poisons right after the strategy meetings, instead of clicking next, you walk around and talk/poison them.
Poisons shaves off a % of the person's hitpoints, making it easier.
