>>533368385
Mari's spirit having to watch her friends falling apart is an underrated genre of anything. Coping with the life she lost while watching her friends lose theirs, Hero being in such a wreck of a state over her death, Aubrey becoming a more angry person as her friends seemingly left her, hearing her father tell Sunny he's not his son to his face, and however she feels about Sunny over what he did and what he's going through. An idea I always liked was her entering Sunny's dreams as Dream Mari and using Headspace as a means of distracting herself from all the bad things just as much as Sunny does.
And even beyond the events of Omori, imagine Mari's spirit hesitating to move on after final duet and sticking around because she's worried and wants to see how things turn out when he tells them the truth, and then Sun In Another Solar System happens, or just any kind of bad case scenario where she can only watch.