What if, instead of a regular Big Bad, there was a civil war among the Slayers? It's a given that Buffy is going to protect and defend Angel, despite everything that he has done during Season 8. A group of Slayers break off from Buffy's more loyal central group and determine to make him pay for the crimes that he committed as Twilight. Buffy refuses to allow them to take Angel, and violence ensues. Making things worse, Xander, who has never needed any sort of an excuse to hate Angel, and Willow, who is embittered because of Buffy's expulsion of Magic from their universe, which prevents her from bringing Giles back are the leaders of the rebel forces. On Buffy's side are Spike, obviously, Andrew, Buffy's core group of Slayers, and, probably, Faith, all determined to protect Angel from execution by staking/beheading/incinerating. Angel's old crew, what's left of it, at least, would also be on his side.
By the end of the season, the majority of the Slayers are either dead or somehow stripped of their powers, Willow has once again regained her magic, probably by way of her half shake girlfriend, gone dark, goes into hiding, possibly in a parallel dimension where time moves differently than at home, and plots her revenge on the Slayers in general and Buffy in particular. Xander is turned into a 4 armed monkey and is cursed to guard the Watchers' Archives until the next Slayer is called.
The Season ends with Buffy still unable to make up her mind between Spike and Angel, but notices that Angel and Andrew, who became close friends during the civil war. are spending more and more time together, and are planning a trip together to Tibet to visit a monastery that Angel knows about.
With Xander's leaving Dawn. unattached and lonely, sets her sights on Connor. Gunn and Rona pair off, and Illyria joins Dracula in his castle as a permanent guest.
And they all live more or less happily ever after.