Growing tired of his son's weak nature, Filbrick forced a young Stan Pines into boxing lessons, hoping it would help him build a stronger character. Though Stan believed it was done simply because his father disliked him, he later grew to appreciate the lasting benefits, later repeating the same process with his great-nephew, Dipper Pines.
He also had Ford, his other twin son, take boxing lessons, seen in the background of Stan's flashback (reading a book, covering his face) as well as in the picture in Stan's car.
When Stan accidentally damaged Ford's perpetual motion machine, ruining his twin's chances of getting into his dream college, Filbrick believed he had done it on purpose, and angrily disowned Stan for ruining the family's chances of being rich. He threw Stan out of the house, telling him he could only come back when he'd earned the kind of fortune he'd cost them.
During Stan's recollection of his childhood in "A Tale of Two Stans," he described his father as "tough as a cinderblock and not easily impressed," though he later admitted to feeling the latter following his son Ford's possible acceptance to West Coast Tech. However, after hearing Stan had destroyed his chances at admittance, he disowned his son and barred him from the family until he could return with the millions he costed Ford.
In Weirdmageddon 3: Take Back The Falls, he is mentioned by Stan when he and Ford lament on their fighting and states that his father was right about him being a screw-up.
From what little we hear of him from Stan within the show, it's implied that he was tough but fair; only pushing Stan so he would be the best he could be. However, it seems that Stan is quite lenient towards him, as Filbrick kicked him out and told Stan that he was "just a screwup".
It's revealed in "A Tale of Two Stans" that he's generally unimpressed with everything, the exception being when Ford Pines was qualified for West Coast Tech. He seems serious about his children making a lot of money, as shown when he kicked Stan out of the family after he ruined Ford's project, causing them to lose potential millions. Both this unimpressed attitude and value for money influenced Stan deep into his adulthood, generating an insatiable greed for cash. Filbrick is also shown to be quite hotheaded and impulsive, as he immediately assumed that Stan had ruined Ford's project on purpose and refused to believe that it was just an accident. In the comics, he is shown tracking Stan down to yell at him and accuse him of stealing. He appears to trust Ford more than he trusted Stan, however Ford's continuous support for Stan in their childhood seemed to irk him.
Stan's father is a robust looking man; he has burly arms, skinny legs, and a distinct cleft chin. Just to the left of his chin is what appears to be a birthmark. He has light brown hair and a small moustache. He wears a fedora, shades, and a dark yellow, plaid suit with lighter yellow lines. Underneath the suit, he wears a blue dress shirt and white tie, along with brown dress pants and black shoes.
- 119. "Dreamscaperers" (flashback, no lines)
"I'm not impressed."
" You did what you knucklehead? "
" I'm impressed! "
- Filbrick was a member of The Royal Order of the Holy Mackerel, but he never told Stan or Ford much about it.
- He and his family were Jewish.