After Askeladd kills Thorfinn’s father Thors, Thorfinn hides inside Thor’s ship and bides his time until the opportunity to take revenge. However, Vinland Saga Episode 5 showed that life on the ship turned out to be harsh without any food or water, which Thorfinn learns that the hard way.
Askeladd is a very peculiar character. Instead of just outright killing the kid, it seems he’s already made up his mind in taking in the boy. Now at first I thought that it could be out guilt of killing his father but after thinking about it a bit more, it may be out sheer respect for Thors as a fighter. If you recall, Askeladd asked Thors to lead his crew. In that moment he really meant it, probably thinking that if someone like Thors were to lead them, they may have a better life. So that’s why he’s taking care of his son. Out of respect for the man he probably admired.
This can also be seen in his son, who despite having the opportunity to kill Askeladd in his sleep, choose not to in order to honor his father’s name. Thorsfinn journey to survive the wilderness wasn’t easy, any other kid would have died before docking, but this kid persevered and kept on going, all in in the pursuit of vengeance. The remaining episode just had him training and learning that the dagger was a better suited weapon for someone of his size. He rematched Askeladd and as expected, got his ass whooped but at the end got offered stance to rematch him, if he did something great on the battlefield.
Overall, the pacing of this episode was great and it helped establish the dynamic that Thorfinn will have with Askeladd and his crew.