I don't know the exact details either, to be honest. There are a lot of potential factors. Most people blame it on the tesseract, but it's not always the cause. Not the direct one, at least. Sometimes it brings in beings that cause trouble and then it's sort of indirectly responsible, I guess.
But the point is, however it happened, I got a few years older overnight. With new memories of the life that went with the age, to boot.
There's not a whole lot else to tell about demons, I don't think, but I don't mind talking about it. Do you have questions that weren't answered by me or by what you've been reading?
Pretty much the only nice things from my world are already here. Sort of. There's not much of anything nice left back there.