"Do you really wish to know?" — Spoilers from the books and/or adaptations to follow!
Dragomir Caldwell was the son of Count Caldwell. After his father was killed at Tuzla Castle and Queen Meve returned in Rivia, he asked her to show him and his family mercy, saying that he knew nothing about his father betrayal.
If Meve shows mercy: Meve showed mercy to what remained of the Caldwells and allowed them to remain in Rivia, provided that his family would have done a donation towards the war effort and fielded a infantry unit. Before going away, he also ordered to remove all the Nilfgaardian vessels from the Caldwells' residence.
If Meve doesn't show mercy: Despite Dragomir's apologies for his father's crimes, Meve ordered the Caldwells to leave Rivia. Before Meve's answer, Dragomir revealed to be a traitor just like his father and ordered his men to attack Queen Meve. In the end, Meve's troops managed to defeat the foes: Dragomir was killed while what remained of his family was escorted in Kaedwen to their relatives.