Originally Posted by
godisawesome
I think Slade's protectiveness of his family initially stems from his pride: they're literally "his people" in an almost possessive sense, and while he probably does have some sympathy and fondness for them, what sets him off when they're attacked is that it's an insult to his abilities. This is why he relies on his warrior abilities to try and free Joe, getting Joe's throat cut, and why Rose and he clearly have a more professional association than anything personal.
Having said that, I don't think we're supposed to see Slade as sociopathically disengaged from his family. Rather, he does love them as people, but he's still so entirely self-focused that he can't quite contextualize that, which is why what we saw of his family life before the attack on Joe seemed unhealthy on all sides. Slade kind of treats Addie and the kids as an addiction he has to feed, but is capable of assessing criticism accurately and seems have some kind of desire for Addie's emotional well-being. He just ignores it when it clashes with his desires. And this issue seemed to imply that he got tunnel vision while trying to save Joe's life, not assessing Addie's hostility until he was shot in the head. In a way, it's the perfect twist on Deathstroke and his family versus Batman and his: Batman's main relationships are formed via his empathy and willingness to unconditionally love someone, while Deathstroke has all kinds of conditions that end up destroying his family.