One thing to think about while writing is the family of your characters. While it’s easy to gloss over the details of your main character’s parents or siblings, it’s really a missed opportunity that can add some fun elements to your work.
Consider some of the interesting story twists like with the ancient Greek myth of Oedipus, or the family relationships found in the Star Wars franchise. Setting these kinds of scenarios up early in your work, as a form of foreshadowing, can make it more believable when you pull off that twist later on. (That villain that’s been gunning for your main character? It’s really his evil twin!)
Sometimes working on a family tree can help with this. It also can be a useful aid to keep things straight, in case the family gets really convoluted (his mother also turns out to be his third cousin twice removed?) And if you’re a science fiction or fantasy writer and throw time travel into the mix? You’d better have something down to keep it all straight, because your readers are probably going to try and figure out that convoluted mess you’ve painted yourself into!
Just something to think about as you move forward. Until next time, keep on writing!