While Alvin is seemingly a caring father to Beverly, he is actually a very abusive man. He doesn't feel comfortable about his daughter hanging out with Bill Denbrough and his friends, Eddie, Richie, Stan, and Ben, as she is the only girl in the group.
He always tends to get very hands-on with her, as well. When he does so, he asks if she is still his daughter. Eventually, this causes Beverly to become fed up with him and turn on him.
Unlike the novel or miniseries, Alvin is sexually abusive towards his daughter, Beverly. After she came home from the pharmacy, her father shows up in front of her and passionately sniffs her hair. This cause Beverly to have an emotional breakdown and cuts off her ponytail, which he notices later after he is woken up by Beverly shrieking due to being ensnared by several tendrils, but is unable to see the blood that just shot out of the sink all over the bathroom. Later, he found Ben's poem in her underwear drawer and gets mad at her. He asks Bev if she is still his little girl, but she finally denies him.
Alvin snaps and attempts to rape his daughter, but Bev fights back, runs into the bathroom and hides in the shower. Alvin kicks the door open and looks for her. Moments later, Beverly bashes him in the face with a toilet seat, knocking him out. Later, Bill Denbrough finds a groaning yet still knocked out Alvin in his apartment, with his blood used to write a message on the bathroom wall saying "You die if you try".
Differences from the source material