I just think theyre much too casual to be considered father-son, and if Reigen really were a father figure to Mob then he'd be a very bad one knowing his previous actions 😅 Reigen was manipulative, taking advantage of Mob's naivety and trying to stop Mob from living a life of his own due to Reigen's (selfish) desire of avoiding loneliness... not a very good parent if you ask me.

I don't think Mob ever saw Reigen as a parental figure either. Reigen would be more of a casual mentor, or like an older brother, if we were to put a label on it... Mob has shown the desire to have freedom to make decisions for himself and have autonomy multiple times, so placing Reigen in a position of power over him (in this case a father) would not suit Mob's desires. He felt constrained by relying too much on Reigen's advice, I don't think he'd find any happiness in viewing Reigen as an authority figure

From Reigen's perspective, Mob would be closer to a friend he grew attached to due to his loneliness, I think also to avoid confronting his own insecurities by projecting them onto Mob in an unhealthy way. I think BPD describes his experience perfectly but that's a different topic. But I believe both of them were too dependant on each other emotionally, almost every decision Reigen would make was because of Mob, and Mob was clinging onto Reigen's words to avoid losing control of himself

I believe their relationship is better described as having a friend with a significant age gap, or siblings with a significant age gap, rather than father-son