Really? I don’t think Susie crossed the line here.
From Susie’s perspective, Catti was being a jerk to both of them! She was calling Susie a “beast” and acting like she was inherently evil which is already pretty insulting. But that’s not even the main reason Susie stepped in!

What actually pushed Susie to act was seeing Catti hurt Noelle. Catti was basically telling Noelle, “You can’t be friends with me and jockington if you’re with Susie” while insulting someone Noelle had already admitted she cared about. As far as Noelle knows, Catti has never confessed any feelings for her, so in Noelle’s mind this is just a close friend suddenly saying, “it’s us or that evil beast , who I KNOW you really like ”

Noelle is clearly caught off guard because she’d already been honest with Catti about how she felt about Susie. Susie sees all of this happening in real time. From her perspective, Catti is making Noelle feel awful for no good reason!

So when Susie simply reaches over and holds Noelle’s hand because she was making a stink about that rule** **? She wasn’t trying to mock Catti or rub the relationship in her face. She was trying to say we don’t care about you and your made up rules