Well, at first she only did it to have yet another group of scapegoats to hide behind. Safety with people who could clearly look after themselves, and her as a result. But time passed, and they had many adventures together, and she realised to her surprise she was actually enjoying herself, and she grew to care for them all. That, despite being pirates, they were kinda cool people, and she found for the first time in a long time she could laugh and genuinely care for someone else's welfare.

And then while they were visiting another island, agents of the government finally caught up with again, and this time they gave her an ultimatum: help them with a job and then turn herself in, or they'd bring an entire war force against that one lone pirate ship. And even though the sensible thing to do would be just to abandon them and run again, she found she couldn't, because she'd grown to care for them too much.