A common metaphor used to describe a relationship requiring equality among three things is the three-legged stool. It quaintly used to refer to Social Security, private pensions, and personal savings/investments as the three legs of a stable retirement financial plan. A Google search can quickly dig up the three-legged stool referring to leadership, management, science instruction, etc. The metaphor is alive and well.
In modern software product development companies, this metaphor is commonly used to describe the way certain disciplines are expected to work together. For those of us working within the discipline of User Experience, we often try to be the third leg working alongside Product Management and Engineering. This is often accompanied by the observation that we're often the short leg of the stool, and that we have more work to do to be treated as an equal partner.
I find the use of this tired metaphor no longer satisfying to describe this particular relationship. In the case of the UX/PM/Eng relationship, it's too passive and it invites extensions of the metaphor that aren't necessarily helpful or natural.
I prefer a new metaphor – a tentpole.
To raise a tentpole, you need at least three wires connected to the ground around it. To keep it straight and strong, you need tension in the wires. Each one pulls the other two towards its anchor, and only when they're in equilibrium does the pole stand straight and tall.
As User Experience practitioners, let's stay strongly anchored in our discipline, understanding our users & their needs, practicing our craft. Let's pull our Product Management and Engineering partners confidently towards our anchor as much as they're pulling us towards theirs. This active tension will enable us all to raise a higher, stronger tent than any one or two disciplines can by themselves.
How about Sales, Marketing, or other disciplines? I'll leave that discussion for another post, but I'm sure the tent's big enough for everyone.