Honestly? Roier did nothing wrong here, he's even being (except for the "I hate you" part) kind about it
He forgave him and when Cellbit thanked Roier for being there for him he thank him back and explain that he was just sad and needed time
HOWEVER I decided that even thou I want Roier's happiness more than anything, I am a Cellbit apologist and Roier should forgive him immediately because what's a little murder? The granpa was just stealing oxygen at this point so... Cell did everyone a favor













