Fa Zheng

Zhang Song's inside man: goes to Jingzhou as Liu Zhang's emissary, presses Liu Bei with the Bo Le parable ('when a person has found his lord, he dies for him'), and at Fucheng joins Pang Tong in urging the strike — 'this is not for ourselves; it is the will of Heaven.'

Fa Zheng; backs Pang Tong's assassination plan; sets up the banquet.

Recognizes the nameless, couch-commandeering stranger in Pang Tong's lodging as his old friend Peng Yang — the identification that checks 'a river's fatal flood.'

Recognizes and vouches for Peng Yang, then draws the map of the two Luocheng roads — found to agree exactly with Zhang Song's — that fixes the fatal line of march.

Writes the surrender letter to Liu Zhang — old friendship, family ties, generous treatment — which its recipient tears to fragments, cursing him as 'traitor, ingrate, and renegade.'

Reads Liu Zhang right ('the plan would be extremely harmful, but he will not do it'), argues for Liu Bang's three mild chapters against Zhuge Liang's strict code, and — as Governor of the Shu District — settles old scores freely enough that Zhuge Liang shields him: 'he added wings to our lord; could we forbid him following somewhat his own way?'

Counsels against recalling Zhang Fei from Wakou, then delivers the chapter's strategic pivot: Cao Cao erred in leaving Hanzhong to deputies — strike now, with Zhang He beaten and Tiandang taken, and Hanzhong falls. Liu Bei and Zhuge Liang march on his word.

The campaign's brain on the ground: prescribes the Host-and-Guest advance that drags Xiahou Yuan out, picks the steep hill west of Dingjun as the perch, and runs the battle by flag — white for patience, red for the charge that kills the Mountain Commander.

Heads the deputation with Zhuge Liang that presses the princedom on Liu Bei, stands with Xu Jing to request the investiture at Mianyang, and is made Chair of the Secretariat.

Memorializes that the Palace needs a mistress — Lady Sun is gone home for good — proposes Wu Yi's high-destined sister, and dissolves the same-clan scruple with the precedent of Duke Wen and Lady Huai Ying.

Fa Zheng; named in passing - Zhuge Liang laments that Fa Zheng's death (off-stage between chapters) means there is no one left whose counsel Liu Bei would heed.