Ok I need everyone to understand that Buck and Eddie are both products of their upbringing. Buck was a child of neglect, which led to him having abandonment issues. While Eddie was a child forced to grow up too fast, which led to him having hyper-independence. Two different kind of traumas. Two different kinds of trauma response. Which would require two different kinds of help.
Buck and Eddie help each other overcome these things and because they are two different kinds of problems, the way they help will ALSO be different. Ever since they met, Eddie has always been there for Buck (don't even fight me on this) and Buck has always given Eddie what he needs. It will look imbalanced, but it's really not. They both need SOMEONE in their lives, just in different ways.
Buck doesn't need someone to take over his lease, or to take care of his son, or to help him figure out childcare, he needs someone to Not Leave Him Alone. Eddie doesn't need someone to tell him he's not expendable, or to be reassured he's trustworthy, or to be promised he's not going to be abandoned, he needs someone to Give Him a Helping Hand. And the moment they became friends they have been those SOMEONES to each other.
They are each other's persons. Equally.