He began as a grunt, but quickly rose through the ranks, becoming an official member at age twelve and a lieutenant several years later, known for his precise ruthlessness as Dirtyhands. He saw Jakob Hertzoon for the first time since the con, only to learn that Hertzoon was really Pekka Rollins, leader of the Dime Lions. He was soon banned from playing in any gambling hall on the Stave thanks to his gift for cards. He worked at gambling dens on East Stave, learned to steal, was sent to jail twice, was courted by numerous gangs in the Barrel, and earned the nickname 'Dirtyhands'. Kaz adopted the surname Brekker, cutting ties with the Rietveld identity and remaking himself as a ruthless fighter. The experience left Kaz unable to bear contact with another person's skin, and after a severe panic attack Kaz purchased a pair of gloves, never removing them except in private.

Barely alive and too weak to swim on his own, Kaz used his brother's body as a float to swim back to Ketterdam's harbor, vowing to take vengeance on Hertzoon. Though Jordie had died, Kaz survived the firepox. Presumed dead, the brothers were ferried onto a sickboat to the Reaper's Barge at sea. When the Queen's Lady Plague swept through the city, Jordie developed a fever from the firepox and Kaz followed two days later. The boys were evicted from their boarding house and forced to sleep on the streets, coming into conflict with the stadwatch and the Razorgulls.

They realized that Jakob Hertzoon and his 'family' had been running a con, taking all their money and leaving them penniless. Kaz and Jordie spent the next week in comfort, but when it was time to reconvene at the coffeehouse, they found it empty.

A few days later, he had Jordie invest heavily in the jurda crop, using all of the funds from the sale of their father's farm. Hertzoon encouraged the boys to invest in sugar stocks, resulting in a large payout. Kaz also met Hertzoon's wife Margit, who served them hutspot, and their daughter Saskia, who gave him her red ribbon. Filip introduced Jordie to a minor mercher called Jakob Hertzoon, who employed them as runners while Kaz remained at Hertzoon's coffeehouse, practicing magic tricks. Several days after their arrival in the city, Kaz and Jordie went to the East Stave to watch street magicians and met a boy named Filip selling wind-up dogs. Jordie sold the farm and took Kaz to Ketterdam, where he intended for Kaz to attend school. When Kaz was nine, their father died in a plough accident. Born Kaz Rietveld, he was raised on a farm near Lij with his father and older brother Jordie Rietveld.

The crooked kingdom series