Incase you didn't know I LOVE Harry Potter! I'm not just a fan, no, Harry Potter IS MY LIFE. So it only seemed right to combine two things I love. Harry Potter and theories. So here ya go.
So as you may know, Sirius Black is the Godfather of Harry. But also he's his UNCLE. WHAT??? HOW??? Now I'm not saying this because he's Harry's godfather, no, just because someone is your godparent doesn't make them related to you. Now if you are a true PotterHead, chances are you read the books. Now I don't know if many people picked up on this one detail, but in the Order of the Phoenix (Chapter 6) Sirius is talking to Harry about the family tapestry, and it says-"'The Pure-Blood families are all interrelated," Sirius said 'If you're only going to let your sons and daughters marry purebloods your choice is very limited, there are hardly any of us left. Molly and I are cousins by marriage and Arthur's something like my second cousin once removed. But there's no point looking for them on here-if ever a family was a bunch of blood traitors it's the Weasleys.'"
So how does this make Harry related to Sirius, you may ask. UM HELLO? REMEBER WHO HARRY MARRIES? OH RIGHT! ONLY GINNY FREAKIN WEASLEY!!! Marrying Ginny basically means that he's related to a lot of people, mainly his enemies. Though his best friends become his siblings in law, most people he despises, he is related to. Like who? Well, remember Sirius? Yeah well remember Bellatrix is his cousin, and so is.... MALFOY'S MOM! Omg! So Harry is related his number enemy? Yup. The only other people that he's related to and doesn't hate is Lupin and Tonks, and their kid Teddy, aka, Harry's Godson.
What makes this even cooler is that Albus Potter (Harry's youngest son) is related to his best friend, Scorpius Malfoy! Bam! Guess what too! They're related to Delphini Diggory! How? Well, her mom is no other than...Bellatrix. WHOAH! Harry is related to Voldemort's daughter! OMG! And yes Bellatrix did marry Rodolphus, but she didn't love him but loved Voldemort, so why didn't she just marry him instead? Voldemort's only halfblood, remember his dad was a muggle!
So tada that's my theory, bye! :3