[Yamer]

I think a good thing to keep in mind with Ellie is that from the first moment we meet her she is angry and unpredictable. This softened as season 1 progressed, and it really seems like Joel was the stabilizing, father figure in her life.

Now that he has (violently) been taken from her, she has resorted back to the angry, compulsive personality she has without that guiding force in her life correcting course.

She's not rational without Joel, and as such those personality flaws are the catalyst to the plot points of Season 2 (and likely going forward). If you don't dig that, the show is probably going to lose your interest and you're going to find the character irritating.