"They all work. But they all have an implied singular definition as well."
Any of the words you thought of could work in the mutual dependancy idea just by adding "co-" on the front since most people are used to this modification of words. eg. co-dependant, co-chairman etc.
edit just changed it to "" since I apparently don't know how to make it blue anymore.

Last edited by Zed; 01/12/06 08:24 PM.