He is a student at North Shore High School. He is a member of The Mathletes and is a part of the Asian Nerds clique. Tim Pak is also a back-up vocalist in Kevin Gnapoor's Winter Talent Show performance.
The film makes no mention of him being related to Trang Pak. However, In the commentaries, Tina Fey confirmed that he is in fact Trang Pak's older brother, which is rather ironic, as the two have absolutely nothing in common and are actually completely opposite when it comes to their personality.
Tim Pak is tall and overall slim young man. He has short spiky black hair, a narrow head and wears glasses. As a part of Asian Nerds clique, he's shown wearing nerd-ish type of clothes.