People who know me probably think I'm almost always a gentle, patient person, and that is what I strive to be, sometimes to a damaging extent because it stops me remembering to actually defend myself when unfairly attacked, or say no when I mean no, or even realise when things bother me. But sometimes when people perceive me as gentle and patient, it's because they haven't seen my biggest irrational enormous rage trigger in action at its worst: abusive/neglectful parents. It isn't kind and it isn't fair and I can usually - in fact, always - remember things like the cycle of abuse and the need to treat people with compassion and kindness in order to deal with these things for long enough to manage the anger and respond appropriately, which is bloody necessary because of my area of professional interest. But whenever my defences are down, whenever I'm not feeling especially patient or kind, whenever I'm already exhausted by compassion fatigue or my own problems, and I encounter a case of a parent who looks at a phrase like "best interests of the child" (which I consider to be flat out sacred and nothing less) with dubiousness or disdain or disgust, when I find out about the things some of my friends' parents did to them or failed to do for them, I ... I feel so full of fury that I don't know what to do. I feel like screaming and crying and going up to fight God for not stopping what happened, I feel like challenging my friends' parents to duels, I feel like becoming a foster parent (which I suspect I should never ever do, but who bloody well knows), I feel like finding someone to drive out to the middle of a field with so that we can scream and scream and scream. There is cruel, unfair, shitty anger in me, and this is the soul and centre of the place where it lives.

"The Best Ever Death Metal Band In Denton", The Mountain Goats

No one was his equal in his eyes apart from Gellert, which was a huge problem for him, because he needed the counsel of someone who was much more mistrustful than him - Aberforth, perhaps, who saw his power and his merits but didn’t worship him, or McGonagall if she felt more empowered to disagree with him and was less prone to the hero worship everyone indulged in when it came to Dumbledore. Hell, Tom Riddle himself, had Dumbledore gone the right way with him, could have provided exactly the counterpoint he needed. Both Dumbledore and Voldemort gathered cults of personality, after all.

If your villain is the most interesting person in your story, you have not written a sufficiently compelling hero. If no one ever wonders whether your villain is right, you have not written a sufficiently compelling villain. If you genuinely can't choose which of them you care about more or want to spend more time with, you're on the right track. If you are no longer comfortable using the words "hero" or "villain" in relation to them, you're where you should be.