Props to the best scene stealer, the reason why the Buffy The Vampire Slayer took off. Its well known that during season two after Spikes first appearance on episode “School Hard” there was an overflow of fan mail for James about his creepy loving relationship with Drusilla. Joss pulled him aside and told him “This is not your show, just know that.”
James asked if that meant he would get more lines and Joss kept him on for the whole season instead of killing him off after two episodes which was originally written. And then after coming back during season three for “Lovers Walk” Joss decided he would become a main character.