Yeah, obsessive is one way of putting it... I mean, he can't even have sex with anyone else. Ever. On the one hand, that's kind of sweet, but on the other - it is a bit unusual.

And I don't think it's too weird for little kid to have some kind of deep emotional focus on any of their friends, but - never outgrowing that? Never looking at anyone else, ever? That's rather more unusual, I'd say. So, yeah. Might be something tied to Locke's super secret past - or it might just be that Locke's wired that way the same way he's wired to want to protect his friends. It'll be interesting to see what happens with that!