I've been recently studying Aristotle's thoughts on friendship in the Nicomachean Ethics, so I found much of interest in Brandon's post on Symphilosophie, or collaborative philosophy.
Among Friedrich Schlegel's fragments is this piece on philosophical friendship:
125. Perhaps there would be a birth of a whole new era of the sciences and arts if symphilosophy and sympoetry became so universal and heartfelt that it would no longer be anything extraordinary for several complementary minds to create communal works of art. One is often struck by the idea that two minds really belong together, like divided halves that can realize their full potential only when joined....
While philosophical debate can sometimes turn into verbal or written combat between individuals, bloodsport, the possibility exists of philosophers working together on a common project, of two philosophers being of one mind. In other words, philosophers can be friends who put aside their various intellectual quirks to help each other out in creating a “communal work of art."