I can imagine both those circumstances, but I am pretty sure they aren’t going to happen, due to the nature of the people in question and our relationships.
I have been close to people with really hard relationships with their parents and children, rarely with a complete lack of love. I often have thought that with some of the things that family members (especially parents) have done, I’d probably be very hostile and/or avoiding if I had parents that did that. They often haven’t, though, even when I’d say they had reason and it’d be a better choice at least until the parent gets healing and changes.
I think though that love is sort of (or can be) a separate thing from horrible behavior and what one does about it. Even with other people’s atrocious parents or twisted children, I get that there is a human inside who ideally would not do what they do, and so I can hold a bit of theoretical love or at least sympathy for them as people who are messed up, even if I wouldn’t want to have anything to do with them in the state they’re in, think they’d best be imprisoned, or everyone might be better off if they fell into a volcano full of molten lava and incinerated.