On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough for The Prodigy side quest.
Rewards: 1,200 XP.
In the place marked on the image above, you will meet a group of lamenting bards. They came up with their own musical, but the self-proclaimed Bishop of the Ruins, constantly criticizes them and scares away the audience.
Turn to the Bishop and talk to him, however, you will not be able to come to an agreement with him. After a short while, the self-proclaimed Bishop will come at you with his fists. Defeat him and the mission will end.