The dynamics between team-mates in Formula 1 can make or break a team. Look at Nelson Piquet and Nigel Mansell at Williams, Ayrton Senna and Alain Prost or Lewis Hamilton and Fernando Alonso at McLaren, Mark Webber and Sebastian Vettel at Red Bull and, latterly, Nico Rosberg and Hamilton at Mercedes: it's clear that having two so-called number one drivers can lead to fireworks.
During my four decades plus of F1, I have seen many different driver combinations at teams. Some worked well, some were average, some didn't go well at all but most were difficult to handle.
Take the Ralf Schumacher/Giancarlo Fisichella partnership at Jordan in 1997 as an example of how fickle team-mates can be. When Ralf was ahead, it was harmony, but when Fisi was ahead it was hell.