I think their relationship is one of the more complex ones in the series, because it is not strictly one thing. Like, they are friends and companions, but they also have a brother/sister-thing, and she acts like his surrogate parent sometimes... I mean, they have so many dynamics, and that is really interesting.
Maybe, like me, he thought that the Bronies might actually be a little nicer to him after he melted that huge iceburg and saved everyone, but noooooo. Nice addition of the slight snot, BTW. XD Adds realism.
Oh, I hope so. ;_; They're addressing character development more and more in the show and according to what I've heard, we've still got at least a few more seasons to go. It has to come up at some point or other, I hope.