Xander is the son of Jessica Lavelle and Loki
It starts after Jessica die's when Xander is 2.

What if Xander's Mum Jessica and Lilly potter were 1st Cousins. they both withes and Xander is Sirius black son. So after Lilly and James are Killed and Sirius is sent to jell and Jessica also dies BOTH Xander and harry are sent to live with Petunia. Both go to Hogwarts in the same year. Xander is the Black Family Heir makeing him very rich.

Xander Goes on his road after season 3 Does not go back to Sunnydale and he becomes a paramedic in Miami. Crossover with CSI Miami

When Xander's 10 years old Mrs Harris is killed and because Mr Harris is not Xander's Dad he is sent to live with his real dad Charlie Epps. After Charlie is told his Ex-Girlfriend Jessica Lavelle is dead and he has a 10 year old son Alexander Lavelle Harris. After season 2 of Numb3rs.

In season 2 Angelus hunts Jessica Harris badly that as she lies dieing in hospital she tell Xander the true about her past & who his dad is. She a witch the only child of Sarah Lavelle a pureblood witch heir of ravenclew & Tom Riddle{from rape}she then tells Xander that his dad is really Regulus Black & that his name is Alexander Lavelle-Black then as she dies cast a spell that gives Xander all her known how about magic. He is then run out of town by Buffy & the other Scoobies for killing Angelus. 2 years later Xander is liveing happily in Miami until found by harry & co he...