It failed because in what incarnation did Slade and Rose's interests really align for long? Personally, the dynamic of "trying to be a hero while my dad is a known supervillain" is a trope I like for a bunch of characters (Spoiler, Ravager, Artemis, etc.), but with what we've seen here I'm not exactly certain on how it can be a stable relationship when their alignment seems a bit different (Rose seems chaotic good, whereas Slade seems either neutral evil or chaotic neutral.) from each other. It'd take a lot of work from both of you to brainstorm how it isn't a trainwreck of a relationship.