Role differentiation (trophic hierarchy) requires N≥3 agents. At N=2 (dyad), the system lacks sufficient interaction topology for emergent role structure: with only one directed relationship, there's no "downstream" vs "upstream" distinction (only A→B or B→A).
Gershenson's E (emergence) predicts: the global pattern cannot emerge from pairwise interaction alone — three-way dynamics (A influences B who influences C who influences A) create the closed behavioral loop necessary for stable roles.
EXP-ASYM showed N=3 PERSONA_LIVE produces stable hierarchy (TR Friedman p=0.008). This experiment tests N=2 with the same personas that had the STRONGEST differentiation (Gamma upstream TR=0.724, Beta downstream TR=0.280). If even the most differentiated pair fails to produce hierarchy, N=3 is a genuine emergence threshold.
Alternative hypothesis: N=2 DOES produce hierarchy because persona asymmetry alone is sufficient — the grounder→upstream pattern operates in any dyad via vocabulary specificity mechanism.