Ulrich had been a member of the Order of the Flaming Rose until Radovid V disbanded the group after using them and taking all their resources during the start of the Third Northern War. Those who remained loyal to Radovid were made witch hunters, whereas those who did not were exiled or thrown into jail. Ultimately, those who didn't join the witch hunters formed into a band of Fallen Knights, of which Ulrich became the grand master.
However, now penniless and with no backing from any rulers, they quickly turned to crime, trading in fisstech, robbing caravans, and murdering people in the Redanian countryside.
If Rose on a Red Field is completed: as his group prepared another shipment of fisstech, the witcherGeralt broke in to investigate and, on recognizing the witcher, Ulrich ordered him killed. However, this ultimately led to Ulrich's death.