They don't finish each other's sentences and when one's had a rough day the other won't have left a vase of fresh-cut flowers on the bench, but in other ways Hamish Bond and Eric Murray are the perfect couple.
The men's rowing pair underlined their dominance on the world scene with an unbeaten 2011.
Unbeaten years are nothing new for these guys; the last time anybody got really close was the 2010 World Championships at Lake Karapiro.
British pair Pete Reed and Andrew Triggs-Hodge pushed them close. They have been described as Bond and Murray's great rivals, but it is an invented concept, because one team always wins, the other always comes second (the head-to-head score now stands at 14-0).
In fact, so strong are Bond and Murray that the Brits - who lead all their teammates in sports science numbers - might be moved to the four to give them a better chance of gold in London.
Bond and Murray defy the sort of easy categorisation that makes life easier for writers and commentators. Bond is a supreme technician and Murray is full of muscle and grunt, but you don't get to be as dominant as they are if those skill-sets aren't transferable. Bond lacks nothing for grunt and Murray nothing for technique.
If anything, off the water Murray might be slightly more laidback. It is certainly true that Bond is obsessed by the need to win an Olympic gold. As one who has followed their careers closely drily noted: "If it doesn't come in rowing, he will get it in another sport. He won't stop until he has one."
Again, that is not to suggest Murray is any less dedicated.
Part of their ambition is borne of failure. They were part of the men's four that won gold at the world championships in Munich in 2007, then bombed at Beijing a year later.
But that is an issue for next year.
The three-time world champions were recently named the rowing crew of the year, beating the all-conquering German eight.
On receiving their latest gong, Murray said: "This year we went 'right, let's just go out and beat them, try to win from the first stroke and don't worry about anyone else'. If people can keep up with us, good luck to them."
It's a simple, but winning, formula.