I think you've actually offered a wonderful template for writing a character who is believable. I don't personally see the point in bashfic and I hope I've never written any. One dimensional characters are boring and unrealistic anyway.

I know lots of B/A writers bash Riley and Spike, but I don't see the point when they are wonderful foils for Angel and Buffy (and other characters) and can be used in all sorts of compelling ways just the way they are.

The best stories are those that present characters that, when you read them, do things that make you go: yes, he/she would say/do/feel that. To ignore the Spike's kinder, gentler side devalues what Buffy saw in him and thereby lessens her character. Everyone loses.

Hope you get some relief for your knees.