I want to add these thoughts:
I am pretty sure that most people in this world experience either more or less pleasure in other human beings based on the behavior of those other human beings; even if they don't actually love them less, they experience less pleasure in the interaction. The funny thing is, I don't. I experience other people as having 'tags' and 'categories' -- people are either 'my favorite' or 'not my favorite', either 'mine' or 'not mine'. Pretty much my entire emotional experience of other people comes down to those tags and categories. I think it's hard for a normal mind to fathom that I will experience another person the same -- and feel the same pleasure in the interaction -- whether the person gives me roses or runs around and squawks like a chicken.
Before I'd ever heard the term monotropic, I was looking for metaphors to describe a way of perceiving the world. One of those early metaphors involved Kitty Carryall: When she was small, Cindy Brady toted around a doll named Kitty Carryall. Once when the doll was lost, Cindy's brother bought her a new one that looked just like the original. Cindy took one look at the doll and shrieked, "That's not Kitty Carryall!" I do so identify with that behavior.
Across my life there have been attachments that are my Kitty Carryalls. Someone either is Kitty Carryall or they aren't. And Kitty Carryall herself just is. The notion that my feeling for a Kitty Carryall -- or the pleasure I derive -- is determined by Kitty Carryall's behavior... well, that seems absurd to me.
Strengths and weaknesses exist as two sides of the same coin. It's hard when the traits I see as my strongest strengths are seen by some others as my weakest weaknesses. I'm sure I have myself at least partly to blame. One thing I did do at points in my life: act as if other people existed solely for the purpose of discussing my Kitty Carryalls with me. That came back to haunt me. Something that stings across a span of so many years... a person who said I was "just looking for someone to be there for me". Ah, not so!