That's not that odd to me since she attacked the boy only to defend her dear plants. She has no reason to remain hostile once the battle in the botanical park is over and the player is done harming her plants. Moreover, Natasha said that she is her teacher and she is a kind woman. Didn't you pay attention to the dialogue between her and Natasha's sister (I forgot her name.)? She (the teacher) told to her (Natasha's sister) that she didn't want to harm people, she only wants to protect her dear plants.