She seems to be a rather appealing character to me because of her messed-up self-image and vindictive nature. A good author would manage to drop broad hints that we're dealing with a scowling idiot ready to take offense and slow to admit failure. A good author would show us that Elly makes a lot of her own trouble because she's sort of clueless and sort of misreads the room. She'd even manage to point out that Elly had an Anthony of sorts who might actually have made her happy when she was off chasing any number of idiots who made her feel bad about herself but made her look good doing it.
Of course, what really sells her as a hero is that your standard git-lit hero is usually the child of parents trying their damnedest despite having a trying child. Mike doesn't qualify really because there are no reasonable authority figures in his life. Elly is an angry, self-pitying scold, John is a thin-skinned bully, Phil is a temperamental shmuck who uses the adjective 'treacherous' to describe children who don't understand the bebop slop coming out of his fat yap and who also let their home life get in the way of devoting all their mental capital to the adoration of an irritating Peter Pan clone and his grandparents are distant nothings. Elly has loving parents who she hates because she refuses to admit that Marian fears spoiling her children.