Shapa is a master thief that prefers to work alone as opposed to working within the confines of the local guild. He also chafes at paying the tribute the guild demands. His skills are legendary when it comes to his art and profession. Indeed no one even knows his true identity. In fact he has been so successful that he really no longer needs income, but now it is simply a way of keeping score for him. In his daytime life he is Lief a successful bar owner. His establishment The Jolly Dutchman is frequented by those of all walks of life and earns a satisfactory income as well. But the night and his alter identity as Shapa always calls to him....
For your character I could see this going several ways: an assassin sent by the guild to finally make Shapa pay, a rival either with the guild or independent entering a game of one upmanship with the master, a journeyman cut purse seeking out the master to better learn their trade, or hell even a bar maid in The Jolly Dutchman who learns there is much more to her boss than meets the eye.
There are many possibilities. If you are interested PM me.