The good thing narcissa did for harry is pure motherly love, after all it's not uncommon to see some mobsters (in movies and real life) defend their families to the hilt because it's the only thing they love, stabbing someone and then paying for the surgery doesn't make you good or make amends, you're just in a vacuous attempt
Draco as an anti-hero, I don't know if I should call him that, do you think that malfoy who never knew who he was could know what he wanted?
I think he's a psychologically affected person and being in a complicated situation he just wanted to run away, give a kid a gun and tell him to shoot someone he's seen all his life (dumbledore's case) and guess how he'll react xd
if the whole thing had happened with a more adult draco who had been completely carried away by lucius and narcissa, he would have killed dumbledore himself, what saved draco from being a villain was his childhood.

But that's just my opinion uwu cheers <3