What remains at the end of it, is a hurt relationship, and a bad job! It could be a Lose-Lose or Win-Lose situation... or anything but Win-Win. I know that's debatable, but leaving all the exceptions aside, here I'm talking about being on two jobs in the same company and not partners in business like Larry Page & Sergey Brin, though I know even that equation has many screw-ups.
The building blocks for friendship and a professional relationship are almost the same, like good attitude, mutual trust and understanding and blah blah blah. In friendship there are times when one friend may even risk personal loss to help another, but in a professional relationship it may turn otherwise. What's the reason?
"Survival of the fittest" operates strongly in the corporate jungle. Well, when it comes to survival, any friend comes after 'ME'. It is not the fault of friendship which fails to work in the cut-throat corporate war. One may surely try to make it happen, but given the many other variables affecting individual performance like the bosses, peers, rumor mill, individual work-orientation, roles among others, it's a complex equation to manage. And yes, the moment you try to 'manage' a friend, YOU HAD IT! Moreover, the patterns of behavior displayed are so very new, different and perhaps even 'unexpected'. And change always gets us, right?
Of course, when you're at work, you can't afford to, and better not keep your focus on friendship, but keep it fixed on work delivery. So, get it clear - if you're engaged in a Talent War in the corporate arena, there's only win or lose, and there are performing teams. No Friendship. No Friends. That's actually not done!