Let's start off with this: 'Trevor Felp' is supposed to reference the 2019 Joker movie with the character 'Arthur Fleck' His story of going into insanity is supposed to somewhat reference the movie, and thus his name was a big factor to it.

Trevor Felp was suicidal. At multiple points in the story, Trevor attempts suicide. Before and after killing the Land owner, he puts the gun to his head. Nearly every time he has a gun, he attempts suicide, which brings the next factor:

After killing Diana, Trevor might have killed himself to be with her. it's a theory that I'm willing to let hang loose for a bit, but think about it- Trevor believed that life was a prison, right? Well after killing his loved one, it would make sense for him to kill himself. Plus, last time he had a gun he tried to kill himself. Why not do it now?

Escape How did Trevor escape the prison? Confirmed: While being sent to another prison (after torturing the guard on multiple accounts, not just one) he escaped. Due to his mental problems that entire factor completely missed in his mind, which brings the next part:

Trevor Felp might not have done anything after killing the land owner. The next part, after killing the land owner, gets super surreal. Details seem to slowly just, poof. Notice how the details, during the scene the land owner shows up, get super, well, detailed? From describing his look, all the way to describing his voice and actions. But how would this happen? Well, Trevor might have actually shot himself.

Trevor's brain was damaged upon being hit by the crowbar. During the scene, while Trevor is being beaten up, the light goes out due to the crowbar smashing the lamp post. This could signify a part of Trevor's brain shutting down. This could result in him gaining all these mental problems. After the incident, he is dazed for a long, long time, as it is noted. This could also be a result from losing half his brain function.

Trevor was originally going to be named Arthur Felp, or Trevor Dallas, or Trevor Fleck. The names went this way and that.

In the original storyboard, Trevor actually cuts up the land owners remains, and spread them in every single apartment room that has children- I cut this out, however, because I believed it was a little to violent.

Why does Trevor have a hat in the cover? In the original storyboard, Trevor finds the 3 kids, takes the crowbar kid's crowbar, and kills all 3 of them. he then takes the crowbar kid's hat, and keeps it.

Trevor never killed the child in the original storyboard for My Smile, Trevor Felp never really kills the child.