There can only be one, masters and heroic spirits(D&D 3.5)
In reply to BrisNoc (msg # 6):
In general, the idea is that heroes would be, well heroic, stronger than normal in order to model the heroes properly (Extra feats, high point buy, MAX HP, allowed to have LA 1+ races, full WBL, any class/PrC combo, access to strong magic items/artifacts/mystical companions) while masters would be more average(read standard, but with more limited resources), and well spellcasters of some kind. For the commoners I was thinking squishy.
The nice thing about being in different teams, is that they remain actual teams instead of just two bodies for basically the same character, and it opens up the possibility for master/servant not to share the same goals, and even turn on each other. But mostly because it allows players to remain in-game for longer, since someone is bound to be eliminated sooner or later.
In reply to Sith_Happens (msg # 8):
I would love to place it in Nasuverse, but it would limit potential players, and at this point the FATE series has gone all over the place with its sources, not leaving tons of space to explore heroic spirits.(I mean Apocrypha felt like it was scrapping the bottom of the barrel) I think that inspired by would be better.