Variants of MUDs in the Identity Related category
A MUE involving an obsession with a factives / factkins source to the point that it causes an obsession with the source, or 'true' self to the point that the person with it feels lesser, or 'emptier' compared to their source. People with SF/SSE often feel like they're just a husk of their 'true' self, or a 1-Dimensional version because their real identity, life, memories, and everything else is still in their 'true' self instead of themself.
Not all symptoms have to be experienced to identify with this, the obsession with source and the feelings of being lesser are the only required symptoms
Symptoms
Coiner@russian-piece-of-shit on tumblr
Link:https://ghostarchive.org/archive/iAhlJ
A MUE involving heavy depersonalization and delusional behavior, which causes the delusion of being a 'side character', 'NPC' or otherwise background character in your own life due to someone else being who you actually are. People with SSD/DE can feel like they're just a husk of themself, or a 1-Dimensional version because their real identity, life, memories, and everything else is in their 'true' self.
Not all symptoms have to be experienced to identify with this, the depersonalization and delusions are the only required symptoms
Symptoms
Coiner@russian-piece-of-shit on tumblr