James: Survived the attack. After Voldemort was gone, he took Harry with him to Number 12. He and Snape co-teach Potions and still hate each other. While Snape refuses to take points from Slytherin, James refuses to take points from Gryffindor.
Sirius: Was proven innocent by James and Remus. James because he was able to testify that Sirius wasn't the secret-keeper and Remus because he knew Sirius never left the house because he was trying to convince his wife to stay. She left him anyway. He and Remus team teach Defense Against the Dark Arts.
Remus: Team teaches DADA with Sirius. He was at Number 12 the night the Potters were attacked and Sirius's wife left him. The three friends became even tighter because of the events of that night.
Harry: Grew up with James, Sirius, and Remus. He was started in training to defeat Voldemort once he was old enough.
Hermione: Sirius' daughter. Her mother tried to take her with her but Sirius fought to the bone to keep her. She has been training with Harry to protect herself.
If you have any questions, just PM me and I'll answer them.