Joss, on Buffy and Angel: "What I always say is: Guys, they're on two different networks. There's no way. Buffy and Angel physically could not exist. If they were on the same network, we would have done the Buffy-Spike thing anyway. But we probably would have had a crossover moment when they would go, "You're sleeping with whom?!" It became difficult in the third year to truly bring change to Buffy and Angel. People want to watch change. Growth. They want climax." [from a Wanda Q&A. i don't think it's spoilery, but don't trust me. stay away!]