**DISCLAIMER: I am not at all a writer, and so if anyone wants to take this idea and run with it, they may. I’m just reading through Half Blood Prince again and got what I believe to be pretty amazing story idea.
Tom Riddle (now Voldemort) goes to find his mother’s family and seeks out the Gaunt house. Finding Morfin, he learns of his mother’s betrayal to her family and where his father and his family live in the Muggle town nearby. He goes to kill the entire Riddle family with the intention of eliminating the Riddle line, but is unaware of his father’s second child, born of his second wife, who has long passed. This boy, the “other Riddle”, was born about 6 years after Tom, and because Tom Sr. either doesn’t remember that he has another child or, equally likely, wants so badly to forget that fact, he’s named this second son Tom Riddle as well.
This “other Riddle” has always been a bit strange, but Tom Sr. believed that to be because he was so gifted and intelligent. He ignores that he is extraordinarily lucky (even to the point of things almost impossibly working out in his favor) or that his friends all seem unusually loyal to him, especially for children so young. After the murder of his father and paternal grandparents, Tom Riddle Jr. (part 2) goes to live at his maternal grandparents’ house, where he is called upon by an unusually dressed woman who calls herself a witch and who brandishes a letter telling him his life is about to radically change.
Fast forward to the second Tom Riddle growing up in his education at Hogwarts, confused by odd looks he gets from teachers and by seeing his name on an award for special services to the school. He realizes that the man that’s rising in power outside the walls of Hogwarts is, somehow, his brother, and after doing some digging, finds out that it is Voldemort’s (as he’s more commonly known now) family on record to have murdered his. Enraged and forever changed by this news, this other Tom Riddle dedicates himself and grows to be an equally Dark wizard, but one in opposition to his half brother, seeking vengeance for the death of his family.
So, what do you think?