Can it be done?

I was just talking with a friend about anime and the topic eventually reached Fate/stay night and then I thought.. "Wouldn't it be cool to play in a campagn based on the War of the Holy Grial?"... so I am here

I have brainstormed some points and I want to hear your opinions on them

Each player will have to characters, one will be the master and the other the servant.

Each player will play his own master character and the servant for another player.

To represent the high power of the servants I was considering to build them as gestalt characters (only the servants would be gestalt, everybody else would be normal).

I am not really sure how to implement the command spells; but since the master won't be controlling their servants directly I think that implementing a rule that the player playing the master character can take control of the servant for one turn three times would work.

The plot would be roughly the same.. with maybe other objectives than defeating the other masters.

So ideas, comments, anything?