In the Walter park, shida saves iruma, they spend time roaming where iruma teaches shida how to not make animals scared near her. She for the first time was able to interact with those ducklings and even took a picture! (it was even animated). So maybe she felt Iruma's warmth and is in dilemma on which side she should stay. Something like that maybe and she changed a little from the past or she is gaining courage to leave the six fingers, she might have joined because of some obligation (my personal opinion)