Tessilan is one of the three men that arrive to meeting with Silke and Garrick, along with Glayde and Faltis. It is possible to kill him, along Glayde and Faltis without reputation loss even after killing Silke, but doing that before recruiting Garrick causes him to not join the party. Taking the Potion of Defense reward after killing Silke by talking to either one of them causes them to disappear, but elsewhere they will stand in the place indefinitely.