Now, where is it written that protagonists have to be completely likable? Of course it isn't, or readers wouldn't find anti-heroes and would-be villains like the vampire Lestat, Severus Snape, Gollum and Dexter Morgan so compelling. We also root for characters who are self-righteous, meddling and simply annoying. For me, that's Emma Woodhouse, but I'd be lying to say I didn't cheer for her HEA. Part of the visceral reaction to characters has to do with how readers relate to and perceive themselves in comparison to the character. When I first started George R.R. Martin's A Song of Ice & Fire series, I HATED Sansa Stark. She seemed the the antithesis of 'family, duty, honor', the very words her mother's family exemplified. Being devoted to family myself, I hated her for doing or considering anything selfish. The all-time, unlikable protagonist for me is still Scarlett O'Hara in Margaret Mitchell's Gone with the Wind - what a bitch! Between manipulating the people around her, always seeking to be the center of attention and hardly caring when her husband died, she is just a hot mess from the start.
What is it about unlikable characters that keeps readers from being completely alienated? As readers, we each draw a line with unlikable characters: there's some fixed point at which all that bad behavior would become irredeemable. Up until then, we're along for the journey. Do we stick around just for the well-deserved comeuppance and enjoy the train wreak to follow? Are we hoping something good will come from life's harsh lessons, a bit of growth and redemption? While we hope for likable characters we can connect with, someone who reflects our personal values, the unlikable protagonist remains compelling. Someone whose intentions and motives rise above his or her actions or perceived attitudes is irresistible. This person reflects the better nature we (sometimes) strive for in ourselves. We all have our flaws and good qualities, but a few characteristics can tip the balance in either direction. That's where I find the appeal of Scarlett O'Hara. Scarlett puts all those ruthless skills to use for the good of herself and family. Protagonists don't have to be completely likable, but there must be some redeeming quality. Therein lies the internal conflict - can an unlikable character triumph overcome the true nemesis, the ugly person living inside?
So, why have I crafted an unlikable heroine? It's a foundation for all possibilities in her life, including triumph over circumstances and perceptions. If I'd written Ms. Perfect Mary Sue in Esperanza, I wouldn't give a rat's ass about her fate nor should readers. The plot gives my main character a chance to rise above, or not. While I don't expect readers to like Esperanza at the outset either, without her imperfections and fears, there would be no reason to care. Without her foibles, she wouldn't seem real.