Pretty self explanatory, would be cool if the further you got from Sanctuary in the UD, the more likely any merchants or travelers or whatever else non-hostiles you find turn out to be aberrant spies, ambushing you when you initiate dialogue with them.
I assume such a system isn't already in place. O_o If it is then disregard this I guess!
Or just friendly illithid and beholder merchants. Not all aberrants have to be bad. :(
The Ordinants will them all dead!
Enthralled random encounters could be pretty cool.
I'm uncertain about an illithid merchant, however, considering how fearsome just one Dread exile has been with his little inn under the sea. Perhaps remote agents, promoters of the Pyrimo who will try to encourage visitation as well as sell you artifacts of insidious horror.
A Mursdwarf, a twitching drow, a lost-but-tragically-found Svirfneblin...
...perhaps even former citizens of Sanctuary and Lower Dunwarren.