I've been thinking a lot about something, re Ultima IX, for quite a while...
The Avatar's been witness to several horrible things: seeing skinned Gwani in Hazard's home, the rampage of the Banes of Chaos in the Serpent Isle, Dupre throwing himself (alive) into a cremation oven to save the whole cosmos, his entire sojourn in Pagan. Pagan hangs especially prominent in my mind, because the Avatar basically has to become like the Guardian to escape: lying, stealing, and murdering across an entire continent to get to the Guardian and destroy him.
These things would weigh heavy on anyone's mind, but from all the story ideas I've seen for various fan-made Ultima IX projects, its never been touched on. Its like he just shrugged his shoulders, said "oh well," and just went on to being the hero. Its his last adventure, we know it, he knows it. I'd enjoy seeing a project come to fruition that has this incorporated into the story as he goes across the Guardian's world toward his final confrontation. It'd make him more relatable, and more human. Thru a good chunk of it, he'd be near-broken from all of the shit he's gone thru, we'd get to see his extreme guilt, look into the trauma his crusade against the Guardian has caused.
I'm not talking a single cutscene or a few lines of dialogue, either. I want visions, haunting visions of these things, I want to see the Avatar genuinely distraught and questioning himself, wondering if he's going to become like the Guardian by the end of all this. I want to see how Pagan, the straw that broke the camel's back, brought him down from being the giant, gleaming hero to a traumatized, regretful, emotional man. I'd also like, at one point, for the Avatar to turn his drive to kill the Guardian into a vicious, unhealthy, hate-fueled quest for revenge. At the end, he realizes that he was always just a man, and ends up giving up his own life to destroy the Guardian and, one final time, to keep Britannia safe.