I love Angela and find her endlessly compelling, lurking at the edges of the action like a malevolent spider observing her web, monstrous to this viewer because she flouts all the rules of what a mother "should " do. Chiefly, she makes very little bones of the fact that she does not love her children in anything like equal measure. Indeed, she openly flaunts this behaviour, doting openly on Peter lest Nathan think she is merely naturally undemonstrative. There are are a lot of complex, overlapping reasons for this, I think but part of the problem is that the Petrelli family is relentlessly insular, demanding that each family member occupy many roles simultaneously. So many in fact that direct contradictions pile up. Some of these roles are mutually understood, albeit sometimes at only a subconscious level but sometimes someone isn't in the loop and so resentment occurs. Angela is full of resentment.