Oh, the emotionally incestous relationship that Sonia and Eddie have sickens me.
Not only did Sonia only want Eddie for herself, she didn't want him to have friends because they could steer him away from her "love", but she also made Eddie believe that his mom is completely right.
Think about it like Ed Gein's relationship with his authoritative mother, it soon turned into an obsession with power and deciding to become his mother and be fully powerful. And he did so using his skin suits made from human remains.
Now I don't believe that Eddie would go that far, but it's similar in the way that their relationship with their mothers is very problematic and shapes their view of power and relationship dynamics.
Also the isolation that both of them faced was detrimental to their emotional development and their way of viewing normal mother-son relationships. Eddie was forcibly isolated by Sonia, from his friends and school for long periods of time with the excuse of his millions of illnesses (even if he wasn't sick at all). Ed Gein was also isolated by his family, he lived on a pig farm with no neighbours and in a house that was covered in animal shit.
Ed Gein is a serial killer and a grave robber, but his relationship with his mother was his motivation to commit those crimes, building up his fantasies and his homicidal ideation over the idea that women were stronger than men and more powerful and the most powerful of them all is his mother.
Eddie kaspbrak had a chance to socialize and to have better emotional skills despite his mother's best efforts, and that was because of the losers. He wasn't fully isolated because of them, and I believe that he would've turned out so much differently if he had contact with the losers during his formative years and adulthood. Their friendship was his anchor.