Part of making a character easy to identify with is making the reader understand why they are the way they are. If a character is just selfish, no one will like them. But if they're selfish because of a betrayal, Because they lost everything they cared about, because they had a rough childhood, the character becomes more human.

Also, I flat out don't write inner monologues for characters if I feel being exposed to their thoughts will alienate readers from them. I'll give hints, like a coy smile or a flick of the brow, but I never let them inside the head of those types of characters. If I need an inner monologue, I'll have another character try to assess the actions of my "mental" one. 

A mental character could also care about characters if they make their life easier. Again, their thoughts wouldn't be very romantic, but it would at least look like they have some humanity.