Warning! Chapter is an author's note, you can skip it if you want or join the conversation. Response to a comment from the Spell and The Key, if you want to read the original comment.
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A/N Sphygmus, I agree Xander needed a cause, a purpose and meeting Buffy and fighting vampires gave him that. I also agree that Willow undermined him with Buffy, we saw a couple of conversations early on between Willow and Buffy that were clearly end runs around Xander and Joss himself described Willow as manipulative from the beginning. Although Willow probably wouldn't have seen herself that way, few people are aware, especially at that age, of their faults. And yes, Buffy needed Xander, she just didn't realized it, but without him she wouldn't have even survived being the Slayer in Sunnydale. At Ieast not without becoming the Buffy we saw in the Wish, cold, merciless and living only for the fight. She often used Xander to make herself feel better and he let her.
I like the Xander and Cordelia ship because they made each other better people, until the Fluke, which came about because the network decided to move Charisma Carpenter to the newly approved Angel spin off and didn't want to move the Xander character as well. That was a financial decision by the network. Charisma has stated she found out she was the lowest paid actress on both shows. Buffy was going into syndication, which meant paying actors more for each episode they were in. Nicholas Brenden was in all but one episode of Buffy, Charisma's salary would have been more if she stayed on Buffy especially when combined with the syndication. Moving her character alone was cheaper because it involved a new contract. Both the character and the actress got screwed badly by the move.
I don't like any of Buffy's romantic relationships because every one of them was damaging to her, with Riley being the best and least damaging, but only because she did treat him like the rebound guy, which he was and not the long haul guy, which he wanted to be and he became more insecure as time went on. But he wasn't planned for by the writers anyway, so they never really fleshed the character out as much as they should have and kept him around longer than they should have because they wanted the audience to accept him, it wasn't happening. All three of Buffy's main romantic relationships on the show were unplanned by the writers and Joss since Angel and Spike were only supposed to on for a few episodes each and then gone. Audience and network pressure kept them around and the writers kept having to come up with ways to make it happen. In real life, leaving aside the vampire thing, Buffy would have suffered terribly in all three main relationships.
People say Xander was toxic for Buffy because he objected to her dating Angel and Spike and they want to believe it was out of jealousy, despite the fact that the writers and Joss scoffed at that idea and Willow as supportive because she encouraged Buffy to get involved with Angel. In real life, Xander would be the friend that tried to keep her from getting hurt and Willow would be the friend that encouraged her to make the relationship work, even when she could see the relationships were hurting Buffy, that's not a true friend, that's a toxic friend.
And Anya, well we agree, she didn't make sense, but that was because she too, wasn't supposed to be around and the writers ignored the original background they'd given her for a long time, while the audience couldn't forget it. I'm really intrigued by the idea of writing a story that makes Anya's presence believable based on that original vengeance demon background the writers mostly ignored for so long. Something similar to what Cole originally was on Charmed maybe, there to study, undermine and ultimately destroy the Scoobies. Cole fell in love with Phoebe and couldn't go through with it, I kinda think Anya as she originally was could have gone through with it, unless found out and confronted.
And as for Oz and how he left, he was a genius and he knew Willow and yes, the way he left was cold and maybe he did suspect she would try something. Seth Green wanted out of the Buffy show, if he'd stayed, would it have been him Willow mind raped instead of Tara?