Family Riku has a family, alright. When he was talking to Sora, he said that they may never see their parents again. So that means that they both have parents. Sora has at least a mom since she told him that dinner was ready. You know they don't live together because in the book it said they're friends and when his mom said 'Sora, dinner's ready!' she didn't say 'boys' or 'sora and riku' or anything like that. Kairi has a father who's the mayor or whatever and a grandma. I think Riku has just a mom since he seems to take care of Sora and Kairi in a sense and is so strong. So he must live in an environment where he feels he has to be strong and take care of himself and his family, so his dad must not be ther to take care of his family. Maybe Ansem could've been his father or uncle or somehow related since some say why did he choose Riku to possess of all people. But Riku was supposed to be the true keyblade master and he was strong and naive to know what was the best for him, so it's not that likely that they're related.