Borch

From Witcher Wiki

Borch Three Jackdaws was a knight accompanied by two Zerrikanian women, Tea and Vea, to whom he referred as his "weapons". He never carried conventional weapons of any kind, saying that he could not, but never elaborating.

Geralt met him after slaying a basilisk. He invited Geralt back to a nearby inn, using the opportunity to question the witcher on his personal philosophy and was pleased to learn Geralt didn't hunt dragons, because, as Geralt explained, they don't threaten humans; rather, it is humans who hunt them.

Borch wasn't keen on killing Myrgtabrakke, the dragon of Hołopole, and later adopted her baby, for in reality, Borch was a huge golden dragon by the name of Villentretenmerth with the ability to change shape.

While Geralt and Yennefer were still unaware that the dragon was actually Borch, Yennefer asked Geralt to kill it so that she might try to concoct a medicine from the carcass that could cure her infertility. Geralt refused.

These events are portrayed in the short story "Granica możliwości" (The Border of Possibility) and episode 4 of the TV series, titled "Smok" ("Dragon"), which was based on the story.