Barry and Hope, the Mikaelson twins. When the twins were born, the witches of New Orleans tried to sacrifice the twins to appease their ancestors. When that failed, they sent Barry to another world in hopes that his magic would never strengthen and he would be forever lost. The Mikaelson's never stopped looking for him. It wasn't until a burst of power was released in the multiverse, that their spells finally worked, well, sort of.