Wren brought the carafe of Tokay which the Master of Jordan College poisoned, without his knowledge. Later, Wren returned to the Retiring Room and stole some smokeleaf when he thought nobody would see. At this point, Lord Asriel arrived. Although Asriel should not have entered the Retiring Room without the Master, Wren did not object as Asriel knew he had been stealing.
Wren was a plump man.
There was an old and established rivalry between the Butler and the Steward at Jordan College. When Lord Asriel arrived and made demands about the Retiring Room, Wren delighted in telling Cawson that he knew more about the events than him.