Just - every historical source describes them as having really dramatically compellingly different personalities: Tiberius is meant to be very reasoned and thoughtful and reserved, and Gaius is supposed to have been passionate and impulsive and fiery. It is forever a disappointment to me that what with the age difference, they never really got to work together in politics, so nobody ever has a chance to talk about how those two opposing personalities interact, and well - two very different people working for the same goal just sounds like it's *asking* for a buddy cops AU to me.

(On a total aside, which made me think of you, there's this shopfront I pass on the tram sometimes, and it says "Barca and Sons, Electricians", and I really hope that when Mr. Barca decided to become an electrician, he knw he was making a pun about lightning...)