On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough of The Poor-Fellow Soldier quest.
Meet The Poor-Fellow Soldier of Christ in Aethelnay.
Travel to Aethelnay
Head to the Aethelnay settlement, which is located in the Hamtunscire area. When you are on the spot you'll trigger a cut-scene. King Aelfred will join Eivor. He has been hiding under the alias of Poor-Fellow Soldier of Christ.
Aelfred will admit that the Order wanted him dead, and he had to act very carefully, and now in his life in exile, he has found a reassuring peace. The man will admit that the Grand Maegester of the Order is him. He hands you the final medallion as proof that England has been cleansed and reveals to you how he came to lead the Order of the Ancients and how he and Goodwin came up with a plan to destroy the organization from within. Aelfred also hands Eivor the key to his studio in Wincestre so that he can understand how much good he has been able to do in England.
At this stage of the game, fast travel on the Assassin's Creed Valhallmap is disabled for about 5-10 minutes, so you have to go to Wincestre on foot or horseback.
Aelfred's workshop will not be marked on the world map, so we've marked the location in the picture above.
Go into The Old Minster, then to the upper floor and through the massive door into Aelfred's studio.
Inside, you'll find a lot of interesting information: a letter written by Goodwin, Alkuin's letter to Charlemagne dated May 10, 804, in which the sender describes all the data gained about the Pagan Order of the Ancients, and Aelfred's comments. It's worth reading all this content, which explains the plot of Assassin's Creed Valhalla.