Grey realized almost immediately that the fifth chain couldn't work like the other four. It wasn't enough for Prometheus to open and close logic gates that Grey had already designed.
The entire logic of those gates had to be capable of changing on the fly, while the number of active pathways increased, decreased, went dormant, or reappeared depending on what Prometheus needed. The chain had to be capable of growing and regressing, advancing and retreating, without Grey rebuilding the mech every time something new entered the equation.
That sounded simple enough until Grey actually tried to picture how it would work, since he could think of a dozen methods to make a chain physically expand and another dozen ways to add modular pieces that could be swapped in and out. But none of those solutions actually solved the problem, though, since they would only change the size or arrangement of the mech rather than what it fundamentally was on the inside.
