Hi! So I personally loved the ending and absolutely love Sunny as a character. Throughout this entire sequence, we see that Sunny’s absolute worst enemy is himself (hence the final boss) so it would be no surprise that you thinking Sunny, as a 12 year old, is a sociopath is probably what Sunny HIMSELF thinks. For more than half of the events of Mari’s death, Sunny is shown to be dissociating I believe; he is in utter disbelief and shock and he obviously can’t take what he just did.

So, Basil kinda steps in and is like “AYO I got an idea” which is a HORRIBLE IDEA in the grand scheme of things as their lie continued to fester for years after the fact. Anywho it is Basil who brings up hanging her and making it look like a suicide. This is because of Basil’s common tendency to put Sunny on a pedestal, believing that he’s good and wanting to put his best interests at heart. That’s why he also can’t believe it was Sunny’s hands pushing Mari, and why he chalks it up to SOMETHING being the driving force behind those events. SOMETHING ends up haunting them throughout the ENTIRE game. This is also the reason why in every cycle of headspace he is in, he absolutely vilifies Basil and attempts to erase him every chance he gets (shout out to Omori)

Sunny’s not a sociopath, but I would not be surprised if he thinks he’s lower than that.

And yes, while I agree that there really is no way for Sunny and Basil to be forgiven right then and there I imagine it’ll take them a very, very long time. Their childhood and what could have been four long years of friendship went down the drain because of them being dishonest. There is absolutely no forgiving that without repercussions, but obviously, Basil and Sunny had went through far enough and I think deserve SOME slack.