It felt kind of out of the blue, that fight. Everything had felt fine. Mostly. Pretty much fine. He had still kinda been chafing under the constraint of not being allowed to rescue his sisters but it was kind of alright. And Zash had been uncomfortable with that and changed the subject when it came up but that was okay. And Yvette was still in retrospect kind of handling him with kid gloves because he hadn't done his think yet. And they'd been snuggling as if everything were fine even though it really wasn't fine.
Okay okay okay it wasn't okay at all he'd just been scared.
He's scared.
What is he scared of?
Is he scared that it'll turn out that Knives was a mistake, and he killed so many people, and hurt so many others, for nothing? That he's just a monster, pain and simple? That none of it was at all different from the way it was when he crashed the ships, which he did because he was a baby and traumatised and terrified and angry and hurting and then it made everything worse and he killed his mum—
Or is he scared that it was the right move, that maybe the crash didn't go as well as planned but there just isn't any way for humanity and plants to coexist? That Knives is in fact necessary? That he and the people he loves will be forever at odds, that Zash and Yvette will hate him forever for what he has to do?
...the answer is obvious, when he puts it like that.