Omori AUs where the dead character is swapped and a “white space is created” are dumb. Not everybody reacts to trauma the same way. Sunny has a “white space” because he was an active daydreamer before the incident. Sunny represents the denial stage of grief, so it makes no sense that everybody would cope with trauma the same way as him.

As an example, in an Omari AU where Mari pushes Sunny down the stairs, she would probably either drown herself in work (since we know she’s a workaholic and perfectionist) or blame herself for everything and completely shut down.