Question: why did uryu join the vandenreich?
Answer: However, it's later revealed that he actually joined the Wandenreich to avenge his mother's death by killing Yhwach. In the beginning of the series, Uryū and Ichigo met on unfriendly terms, though after a competition to see whom can slay the highest number of Hollows, Uryū became an ally to Ichigo and his friends.