Answer
Cousin. Jogaila and Vytautas were cousins, specifically first cousins once removed, as their fathers were cousins. They were both members of the Gediminid dynasty, a powerful Lithuanian family. Jogaila became the Grand Duke of Lithuania in 1377, while Vytautas served as the Grand Duke from 1392 to 1430. Despite occasional conflicts, they maintained a close relationship and worked together to expand and strengthen the Grand Duchy of Lithuania.