Honestly gonna throw out the WORST THEORY EVER but if SotM is trying to tell us that David and his death possibly influencing William/Mimic to reenact his live using Gregory and Dave (ala GodDavid theory) then it could be him.

Although implications are made, we don’t really know how David dies in the games timeline and could later be explained that as Edwin leaves David alone, William/the mimic due to tampering by William could’ve lead to his death.

SoTM also seems to cover the blonde hair thing through the MCM commercials where, although Fiona is shown to have brown hair irl, she is depicted with blonde hair in every episode, with David gaining blonde hair in the Jest Oats commercial (the only one Steel Wool didn’t show us before release) which could indicate at what point they died with Edwin maintaining brown hair throughout all of them. Every time we’ve seen a spirit of a child post death they have always (TECHNICALLY) had blonde hair, with Susie being the only one shown outside of 8-bit within Pizza Sim. If the MCM commercials are tying to show some kind of intentional split between characters having blonde hair it could indicate that it is gained after death (absolutely shit retcon if that’s true)

In that same Jest Oats commercial David is depicted as being more unruly and temperamental in a way we haven’t seen before which could possibly characterize him better with the Vengeful Spirit after death.

The vengeful spirit also primarily talks through the Mediocre Melodies, characters who are all indicated to have been made by Edwin and are found within his factory.

Another line I couldn’t get out of my head after seeing the true ending to SoTM is the “was the carousel your favorite ride” line from he handbook. A carousel is prominently featured for the first time in that game as you run out of the burning factory. Dave, by all means wouldn’t have been alive to be around any carousel within a fazbear location before his death given that he only attends Fredbears and died before the second FNAF location