I just hate how people tend to soften or romanticize the Darkling, justifying his traumas or good motivations. Like, DUDE, this man is evil. Yes, at one point in his life, he was a good person with good intentions, like making the Grisha respected and accepted. BUT he became corrupted over the years, and after using merzost, he's a horrible person, and Bardugo reinforces this several times in KoS and RoW. This is the same man who willingly let Genya be raped, encouraged Zoya directly and indirectly to be a bad person, manipulated a 17-year-old Alina who was clearly desperate for love, BLINDED his own MOTHER, punished and killed several people and THE GRISHAS THEMSELVES. HE KILLED THE PEOPLE HE SWORE TO PROTECT, it's in the books, he is not a good person, he doomed Ravka and the Grisha. In KoS, we see the destruction he caused in Ravka and how the Grisha continue to be frowned upon and die, and indirectly, he helped the enemies of Ravka and Grisha grow stronger and go after them. If it weren't for Nikolai, Zoya, Genya, and everyone else, there would be no Ravka, no Grisha. It doesn't matter if he was once good—he was—but focus on this: he WAS good, he HAD good motives, he tried to fight for the right reasons, but he was corrupted and took everyone with him in that corruption.
Yes, Darkling is an extremely complex character, but he is a villain, a very well-constructed villain. THAT is his nature. There is no gentle, weak soul struggling to escape his cruelty. He is cruel, accept that.
