Well basically you were both volunteers in this Wayward Star experiment (think sorta like the Assassin's Creed series... I think. I've never played it, only caught hints at the overall plot, but from what I've seen it sorta fits). The idea was to conquer the Aether, to bend it to one's own will. After all, mankind had already conquered the natural world with magic; why not take control of the supernatural as well? The Realm of Dreams was as good a place as any to start.
The experiment was presided over by your bumbling friend Deyn here (who happened to be a high-level Cleric, had you managed to somehow convince him to tag along into the Aether. The drawback would've been a newer and slightly more maleficent overseer in the real world). The book was actually Deyn's idea in the first place, trying to keep you from wandering into places you should not yet have gone (because as he said at one point, dying in the Aether would not have ended well for your real world body). He lost all memory of it as well, in accordance with your unexpected setback with the alternate selves.
Ross had the right idea when they showed up; they were in fact iterations of your "future" selves, but in the sense of Aether time that wasn't far off (at least in my head that's how it plays out... tough to explain). They are considered a problem because 1). That sort of thing only happens at the behest of a controller, which means your session in the Aether had some outside influence that was potentially dangerous in the wrong hands, 2). they could have told you a great many things that would've become problematic and possibly caused paradoxes (thankfully, they did not realize that they were staring at their past selves, so they didn't manage to bumble into any conversation topics that would've ended poorly), and 3). They were headed off into a fight that you guys could not have handled (as in, they died in that fight, and you would have joined them had you been able to follow). The dual influences over your supervised trip into the Aether resulted in a loss of memory, both in regards to Deyn, yourselves, and your would-be antagonist. Unfortunately, that guy didn't have any notes. I did not know who he was, nor did I have any ideas regarding it at the time, haha. He far enough in the future that I didn't have to worry about him, so I didn't.
I had a ton of other notes, too, but those sank along with the motherboard on my old laptop... that's all I remember of it. If there are any plot holes, point them out and I might remember snippits more.
It's bit a convoluted and roller-coaster-y, and I apologize for that. A lot of my plots are very... stream of consciousness, as my brain decides "Oooh, I can do this!" and then I write it down and find some way to tie it in later. There were a lot of twists and turns that kept you guys going "What. The. Fuck. Just. Happened." It was sorta planned that way initially, but it was never intended to reach this level of... intensity.
EDIT: The metaplot had something to do with a grizzled Archmagister who had been trapped in the Aether by a previous Wayward Star experiment, and the pure essence and length of exposure to the place corrupted his mind... the rest of that train of thought is lost to me, though. Dunno where it was going or where it ended up in my notes, because like I said: poof.
EDIT 2: Feel perfectly free to use your imaginations and fill in the missing parts, hahaha. I'm sure you could spend a solid hour or two piecing things together like that.