Lore summary based on what I see and remember:
The Mirage first broke out from the moon, it first infected default.
It later than spread to the other default stickfigures.
The Mirage has some stages:
First phase: Black part on the infected body somewhere
Second phrase: bloodshot eyes, small eyes appear
Third phase: Eyes dilate, become grey, and the eyes become larger
Fourth Phase: It is unknown what this phase resembles at this time.
…and that’s all I remember, if there’s anything I missed/got wrong, please let me know and I’ll add addendums in the comments
Anyway Infected Default wearing the Don’t Come Back. fit & pose