Caster, actually. Caster is a class for those who can imagine great things into reality, so you see a lot of artists and authors there. Though someone like Da Vinci might classify as a Rider too. Wasn't she known for trying to invent flying machines?

['She'.

Bedivere took the cup of tea with a quiet thanks. He didn't go for the alcohol yet, instead preferring the warm, mellow drink that late at night. Not that he needed to sleep or anything, but old preferences still leaked into his behaviors as a heroic spirit, and he was never one for getting drunk and rowdy. The most vanilla of the knights, this one.]

Valhalla...I suppose that's a fair comparison. Though there was a lot less 'fighting' and a lot more 'waiting'. I think a lot of heroic spirits used being summoned for Grail Wars and such to sort out their disagreements.