I’m not going to articulate this well. but like. buck doesn’t see himself as chris’s dad and he has never seen himself as chris’s dad.
even though he has loved him like his own child since at least season three, eddie is chris’s dad, and chris doesn’t need another parent. at any time, eddie could remove chris from buck’s life and there would be nothing buck could do about it. I don’t think buck thinks this will happen, but I think he is acutely aware that his place in chris’s life is technically undefined and entirely dependent on his relationship with eddie (which is also. undefined.), and I think he is very careful not to make any assumptions about his relationship with chris or cross any boundaries, in part because he would never want to imply that eddie is not enough for chris, and in part because of what chris being essentially buck’s kid would mean about his relationship with eddie.
and chris doesn’t see buck as his dad either (for entirely different reasons). he loves buck, he knows he can count on buck and that buck will always be there for him, but to chris buck is and always has been his buck. not his parent. I think as their relationship stands now chris will look back when he’s a bit older and realize that buck was like a parent to him. but as it stands I think he’s young enough and close enough to it that he doesn’t really interrogate buck’s place in his life.
I think the person who sees buck as chris’s parent/chris as buck’s kid the most is eddie, in that I think he recognizes the most that buck is an incredibly important person in chris’s life, and he feels completely secure about buck’s place in chris’s life. he tried to share that security with buck in the form of the will, but ultimately I don’t think that ever settled that way in buck’s brain. I think buck has always seen it as a display of trust that buck will be always be there rather than a promise of security that buck will always be there . like chris and eddie kind of take for granted that buck will always be around, and assume that he knows that they’ll always want him around, but I don’t think he really does. due to his issues.
so it makes sense to me that buck would want to take on a more clearly-defined parent role (not that his role in Theo’s life is any more defined right now, but I digress) AND I think it would be a super interesting conflict to explore how buck wanting/having a(nother) kid would affect eddie (who has always felt that buck had a secure place as a co-parent in chris’s life) and chris (who has never really had to interrogate buck’s place in his life before but might find himself doing so now)
(unfortunately to explore the undefined nature of buck and chris’s relationship that they almost necessarily have to explicitly explore the undefined nature of buckandeddie’s relationship which they are. allergic to doing. so we shall see)

















