- "History only only remembers them as Blood and Cheese."
- ―Catelyn Stark
After Lucerys Velaryon was killed by Aemond Targaryen, Lucerys's stepfather Daemon Targaryen hired two assassinates to kill Aegon's and Helaena's children, Blood and Cheese. Blood was a former "Gold Cloak" and Cheese was a rat-catcher who knew all the sewers around King's Landing. This meant that they both had perfect recognition of the layout of the Red Keep. After breaking into the royal apartments, they found Helaena putting her children to bed. They demanded a son for a son. Helaena pleaded they kill her instead, but they refused. She named her younger son Maelor as the victim, prompting Cheese to sadistically tell Maelor that his mother wanted him dead. Some believe that Helaena named Maelor because Jaehaerys was heir to the Iron Throne, or because Maelor was just too young to understand. However, this request became an act of defiance against the Greens, as Blood beheaded Jaehaerys with a single blow. By the time the guards came, the Queen was cradling her son's body. Jaehaerys's death would eventually led to his mother's insanity and suicide.
In the books
In Fire & Blood, Blood was a big, brutal hulking swordsman and likely a rapist. He was a sergeant of the City Watch of King's Landing, but he lost his cloak when he beat a whore to death in a drunken rage. Following his dismissal, he spent time in Flea Bottom.
Once Prince Lucerys Velaryon was killed by Aemond Targaryen in the Dance Over Storm's End, Blood and the rat-catcher Cheese were hired by Mysaria, Prince Daemon Targaryen's spymaster, to kill one of King Aegon II Targaryen's sons in retaliation. They ambushed Queen Helaena Targaryen and her children in the Tower of the Hand and ordered her to choose which of her sons would die. She offered herself, but they refused and Blood threatened to rape her daughter Jaehaera Targaryen if she did not choose. She chose her younger son Maelor Targaryen, deeming him too young to understand the situation, and Blood instead decapitated her elder son Jaehaerys Targaryen. Blood and Cheese then departed, taking the prince's head with them.
Blood was later captured and tortured for thirteen days till he finally died. Cheese, however, got away, and no trace of him was found.