>>536872006
In the photos and stuff Sunny is usually standing at the side with a vacant expression, reading a book, or playing vidya while his friends are talking and having fun. Sometimes he's napping or actively ignoring/hiding from his friends. Like in picrel, which is literally the photo where Basil gushes about Sunny being a great listener, and in the same breath he says that sometimes he feels like he's bothering Sunny. In the real flashbacks Sunny still doesn't talk. So no, he wasn't exactly talkative in the past. He's not that great of a listener either if people who vent to him feel like they are bothering him.

>the guilt of what he did
Caused by Sunny killing Mari.
>the bullying
Caused by Sunny destroying the album and making Aubrey lonely and miserable cause look above.
>his grandma dying
Sunny poisoned the grandma. Ok he didn't.
>and Sunny about to leave the town
After 4 years of ignoring Basil and their horrible shared secret Sunny suddenly appears, gives Basil false hope, just to reveal that's he's skipping town in 2 days. No wonder Basil freaked out.

>Basil decided on his own to desecrate Mari's corpse and manipulate a barely cognizant Sunny into helping him carry the body outside, so that's entirely on him.
Sunny manipulated Basil first into helping him carry the body upstairs. Sunny was also initially relieved when he saw Mari's hanged corpse. So part of Sunny was grateful to Basil for covering up for him.

>Despite that, Sunny still decided to confront him and save him from himself, knowing that it'll snowball into the truth finally being revealed to their friends.
What a great guy.