Had a random Deltarune AU thought after seeing some theories about a connection between Susie and Everyman:
Susie does some kind of heroic sacrifice to break the prophecy that goes awry and results in her getting ejected from reality goner style and stuck in a time loop purgatory watching the world go through the Deltarune plot over and over, only she's not a part of it.
She's effectively a ghost who's unable to interact with or be seen by anyone. Nobody seems to remember her, and yet the prophecy proceeds as planned every time as if she were never needed at all. Over time as her hope dwindles she becomes duller and greyer and her unique features begin to melt away until she begins to resemble the Everyman sprite.
Then, when her identity has been all but washed away and she's nearly resigned herself to fading away entirely, someone finally sees her and interacts with her, and it's none other than Mr. Generosity himself!
Lancer doesn't know who she is but he likes her vibe and starts hanging out with her (perhaps she still can't speak to him in her current state and he comes up with some silly nickname for her). Lancer's company ends up reigniting the spark in goner/everyman Susie and the two of them go on an adventure to try to break the cycle and fix what went horribly wrong here, acting in the background as the Susieless prophecy plays out once more.
Will they finally be able to break the prophecy? And will Susie regain the life that was taken from her after her prior failed attempt to do so? Idk and I don't have time to actually make this a story but it might be cool to draw a goner/everyman Susie design.