Okay, I have another one for you

This was read a long long time ago and I can't remember too much about it. I do remember that it was post Chosen, maybe also post AtS (?). Spike is an angel (as in heavenly being) and it is revealed in a scene where everyone is gathered together (it was very dramatic). Might have had something to do with other characters questioning his...goodness (don't know if that's the right word) and mistreating him.
Hope it rings a bell with someone, I'd really love to read it again.