"They're a gang of five. They've got each other's backs.

When one is taken down the others will rally in support. They're the sum of the whole, not just the parts. They don't form factions and "Frank and Gerard" ranks no higher on the food chain than "Gerard and Ray" or "Ray and Mikey" or "Mikey and Bob" or "Bob and Frank".
Of course, they know what happens when they're not a gang of five. They know what happens when the team falls apart, when the sum of the parts is like a jigsaw gone to decay.

A gang of five. Not two, three, or four."
A progression in ten steps, Restriction