Not Even Once - Sean

Hi guys, I'm trying to finish the game with Not even once achievement so no civilian kills. Anyway, looking back to chapter 3 with Sean, I didn't had any experience to use the bloodlust and obviously I didn't killed him so I spared him But since he turned into full Skal and then I killed him, does it mean my achievement is f***ed? Thank you

I still got the achievement after:
sparing Sean, and killing the skal version of him
turning people into vampires
fighting and killing this one vampire dude from a side quest
and having people die in the district because of the low health levels there or whatever you call it, so I think you only miss out on the achievement if you embrace (drink from) people that aren't the creatures and guard of priwen dudes that appear on the streets, so just don't embrace the people you can actually converse with and ask questions, like Sabrina from the bar, you wouldn't get it if you embraced her.

Or I think so, anyway...

Correct, the achievement is for Embracing, not for just killing. You should get the achievement if you get through the game without embracing Citizens.

You do also need to not kill the vicar during the boss fight he takes part in, too.