@JWChibi 'Cause her mom was messing with her will first, making her dislike dragons and stuff like that, general influencing. I think for lower power spiders the mom just mind controls them straight up, too.
I don't remember if it still effects her now or only when she was lower level, but either way she took it personally and was like "I should get rid of mom so mom can't influence me". If she is still vulnerable on some level, then she wouldn't be safe even on the surface anyways.