Who is Allan Geller from King of the Screwups and what is their importance?

Allan Geller is Liam's father. He grew up in Pineville, New York, and he is estranged from his brother. Allan is a professional financial genius, and the CEO of MoneyVision. While he excels in his professional life, he is a bully and a tyrant in his personal life.

Liam tries hard to impress his father, but no matter what he does, Allan just gets angry and voices his disappointment. By the end of the novel, Allan is losing his power over both Liam and Sarah.