Bertrand Welch Timeline and Summary

Bertrand shows up at Professor Welch's (his father's) house for the art weekend and to meet a wealthy art patron who might have a job for him.
He seems to be a guy who always needs to be the center of attention.
We get a first look at his hot temper when he gets mad at Jim for mistaking his girlfriend Christine for one of his exes.
Bertrand and Jim keep arguing with each other for the rest of the afternoon. Bertrand even asks Jim to step outside for a fight.
Later that evening, Jim glances into a room and sees Bertrand making out with a married woman named Carol Goldsmith but decides not to tell anyone about it.
Next time we hear from Bertrand, Jim's calling him on the phone and posing as some reporter asking about Bertrand's paintings to get the inside story of who he's taking to the University Summer Ball
Bertrand had planned to take his mistress Carol, but when Christine finds out he's going to the ball, he dumps Carol for Christine.
Bertrand finds out that Jim has gotten a taxi and taken off with Christine.
Bertrand barges into Jim's room and tells him he knows all about his meetings with Christine. Jim says he won't back off, so Bertrand tries to fight him.
He punches Jim in the eye, but Jim knocks him to the ground and ends up winning the fight.
The last we see of Bertrand, he's standing outside the train station with his mother, father, and brother as Jim walks by arm-in-arm with Christine. We can only imagine his reaction.