Harrison James "Harry" Potter, Brother of one, and son of Lily and James Potter. He is the hated twin, the one who does everything for the others. He is abused and treated like a house elf by his mom more then a child should, while his father has mixed emotions and just follows his wife when shes around. He is the oldest Child.
Charlie James "Charles" Potter, the younger Twin, and one of the spoilt brats all Slytherins dispise. He thinks everything should be handed to him easily, which is usually from his Mom and Dad. He hates the Slytherin house, thinks Ravenclaws are 'Nerds', and loves making Hufflepuff cry. He also hates his brother, thinking that he is weak and that he is a despise to The Most Ancient And Most Noble House Of Potter.
James Fleamont Potter, Father of two and a husband of Lily Potter. He loves both of them equally, well, he never dared to show it to Lily (which actually happened). Yes he may be nice to Harry, but he never actually realized it much. He loves to spoil one of the children, while he only gets things for the other if he speaks up. Of course, he doesnt most of the time.
Lily Marie Potter, Mother of two and a wife of James Potter. He loves her children, by children, she means the Boy Who Lived. She absolutely hates her older Child. When she did, that was before the fame of her Youngest.
'Opposites'
Harrison was opposite to his sister- Hope- in every way: Where she could barely control her magic, he could summon things when he was only one; where she was trained by tutors to defeat the dark lord, he was in the past getting trained by the founders; And where she was giving her life for the light, he became a new sign of hope for the dark.
or
Wrong G/BWL Au, Harrison time travels to the past to grow up with the founders only to go back to the future a day before his first day at hogwarts. He decided that the dark side shares more of his ideas than the light side and eventually even finds love in the man his sister is trying to destroy.
(This sounds so sappy, I promise it's not.)