Willow/Spike/Angel(us) by Cat
One of the most unusual pairings amongst BTVS/ATS fans, is Spike/Willow/Angel(us).
It's interesting because you have three _very_ different personalities.
Willow: mattering when you place the fanfic, you have to deal with a different persona. Whether it be a shy young teenage Willow in the earlier seasons. Or a rather more powerful Willow in the later seasons.
Angel(us): If you're dealing with Angel, you also need to look at the timeframe. Unless you dramatically alter his relationship with Buffy during seasons one, the begginning of two and three. Any relationship with Willow would be unplausible. Afterwards however. You have guilt stricken vampire with a soul working towards redemption.
Unless you're dealing with Angelus.
Unlike his souled counterpart, Angelus is not a nice guy. He's cold, cruel, manipulating, and has no trace of humanity. His likes to hurt people. how this works is up to you.
But remember, though he is a demon. Angelus still has the capacity to love. and to hate.
Spike: Now Spike has three, in some cases four different personalities on the show. First is completely evil Spike that shows up second season. Next would be Evil but pathetic chipped Spike. Third is "completely in love withthe slayer" Spike. Last is seen season seven and that is ensouled Spike.
Now if you mean to portray ensouled Spike do _not_make him a mock Angel. He isn't Angel they have very different personalities.
Other than that just use the show as your guide.
But after reviewing the characters you realise that between the three of them tension would arise.
Of course it would! There is always tension. Things are made even more...complicated by Angel's soul, or rather his curse.
If you want to portray a relationship between Spike, Willow and Angel try to do it realistically. Do not just have Angel jump into the sack with Spike and Willow. We all saw what happened last time he got too happy .
The relationship between the three would be strained depending on when you place it. You can deal with Spike's chip, Angel's soul being put back, Willow's addiction to magic, even Spike's new addition of a soul. So yes. There is bound to be conflict.
But that is what makes a story great!! Plotline!
Without Plotline, without conflict you have fluff. While cute, fluff is not the kind of stuff awesome stories are made of.
These are fairly untested waters. What does that mean? It means that the fans of this group are rather smaller than other pairings. It means that if you don't want to be ridiculed you need to write fanfiction that shows everything a Spike/Willow/Angel relationship could become.
But, be careful. While testing these new waters don't caught up in stereo types. It matters when you place the story. If it is post season seven, and a Willow/Spike/Angelus it is going to be radically different from what we saw in season two.
Willow is extremely powerful, enough to even awe Angelus. She is not the gangly frighteneed teenager that he used to know, as a fanfic author we must adjust to this.
There are bound to be conflicts between the three of them. For example Angel and Spike's knowledge of Willow's previous magic addiction or Angel's realisation what Spike almost did to Buffy.
How they interact is up to. After all, that is wha fanfiction is all about!
But please remember a few small things. Over the seasons all of the characters have changed. The way they might have interacted at one point is no longer the way they _will_ interact.
So keeping that in mind, go and test the pairing of Spike/Willow/Angel(us)
 Angelus is considered completely devoid of humanity by the judge. Who was created to tell these things. Season two, I'm not sure what episode.
Season two, Angel got too happy, and poof gypsy spell induced and no more Angel. In fact instead we got his homicidal souless companion. Angelus.
 Spike almost raped Buffy near the end of Season six. I'm not sure of the episode. It might have been entropy.
The authors own nothing. Joss, UPN, WB, etc. own Buffy, the show, the characters, the places, and the backstory. The authors own any original plots.