Rig did not accept the job Ned was offering, yet.
He was considering the job. But not the job itself even though he even didn't hear what it was. He was considering it because it was offered by Ned.
Looking at the two alone, Ned was like a kid and Rig was his uncle just from the towering height of the Wood Rank Hunter that stood nearly 7 feet tall.
Normally, Quest and Job came from the officials of the Hunters Guild, Noble Houses, or someone whose credibility was remarkable: like Master Claire of the Forgotten Pint as Provider of Quests.
Ned explained that the job was simple. He needed information regarding the sewers or undergrounds of the city. Something, or somewhere inside that leads him to either the Canton of Commerce or the Great House of Soak.
And if Quentin was right, he might find what the Hunter's Association were hiding.
