Yalb is a sailor on the Wind's Pleasure from rural Thaylenah. He accompanies Shallan to the Conclave in Kharbranth, translating the porter's comments for her and refusing a bribe to gouge her on the price. She paid him a fire emerald for his aid and, later painting him, tried to capture the way he had flirted with her. When she returned he had won eighty chips off guards by cheating them at kabers.
He helps Shallan buy books for a very good price by conning the bookseller Artmyrn into believing that he - Yalb - is an agent of Barmest (i.e., Artmyrn's biggest rival) who can offer the books Shallan needs at a lower price, again showing his skill at deception. She rewards Yalb for this by giving him her painting of him and the porter.
He believes in the passions, a pagan belief that one wins most when one needs to.