Jeez, yeah she's a sociopath. Makes sense though, a death god wasn't gonna teach her 'killing humans is wrong' that's their whole MO, and realistically 'killing humans' isn't wrong from the perspective of non-humans. Of course, she is a human, but well she wasn't particularly raised as one, not with a single human moral.
Sorta like if a rabbit was raised by wolves and taught to eat other rabbits, like yeah it's cannibalism but the rabbit wasn't taught with that frame of reference.
Anywho, from an outside perspective she's just edgy for the sake of edge, but from in character it's not like she revels in killing, she just wasn't raised to have any reservations about killing either.