Commander Sophia
Commander Sophia spared the team's life on this first day in return for the meat of a wolf that they helped kill. She was a little charmed by Corra.
Tanya
The self proclaimed "Leader of the Map Gabbers", Tanya had a way with words, and could convince lots of bards and rogues to follow her lead through the hall as a merry gang of fighters.
Little Timmy
A child who had been down in the halls for so long that he had forgotten his own name. Teleporting around at random, eventually Timmy got trapped in a corner of the halls that were completely sealed off from other rooms. The necromancer took Timmy's spellbook, and kept the kid around to lull him out of his stupor, eventually getting Timmy in quite a good mood that when Vadim's brain got wiped, Timmy tried to teach him back each lesson.
Moses, Louis, & Jerome
A ragtag group of penniless and powerless jerks, these three stooges only had one claim to fame: They had found a futuristic tablet which allowed them to take notes on a notetaking app. Moses and Jerome were desperate to stay warm, having arrived from The Arctic Autumn, while Louis appears to have been banished sometime during The War of Many Names, and had a cursory idea of how the tablet could be used.
The three of them had been in the backhalls for a whole week, long enough to learn a few things, and pass on that knowledge to the PCs. Unfortunately, they weren't great fighters, and wound up dying at the hands of a random encounter with one of the Vestiges of the BackHalls