Brian ("A Hat Full of Sky")
Brian is a failed student who dropped out from Unseen University after a couple of years. This does not stop him seeking a career on the fringes of magic, but he has stepped outside the accepted roles for a failed Wizard - Thaumaturgist, for instance - for something he is yet to realise is infinitely more dangerous: assisting Zakzak Stronginthearm in selling magical items of dubious provenance to young women who are - for now - gullible trainee witches, drawn to Zakzak's Emporium by that most potent magic of all, adolescent female peer pressure. He might just be better off going out on expeditions to collect 10cc of fresh tiger semen or uprooting mandrakes and risking their subsonic squeal of agony doing irreparable things to his lower bowels, as Tiffany Aching, under the possession of the Hiver, gives him a lesson in applied magic he is never likely to forget. (Nor does Annagramma Hawkin or any of the other novice witches watching).
Brian loves the shop, appreciates being surrounded by young women (who pay him scant heed as he's not what they are there for) and really doesn't deserve being the subject of a magical transformation.
In fact, under severe questioning, he breaks down and admits he never graduated from UU and is not in fact a wizard. Still more, he shamefully explains he actually studied fretwork at the University. Now one of those odd coincidences is that one of Rincewind's lesser academic titles as part of the Faculty of UU is, in fact, Professor of Fretwork. Could Brian and Rincewind, at some point at UU, actually have been known to each other, maybe recognised a sort of kindred spirit?