Elden Ring Rogier's Quest
First Encounter with Sorcerer Rogier
You can find Rogier inside Stormveil Castle, where Godrick the Grafted, the game's first story boss, is located. You'll find it wandering the rooftops of the castle and entering a church-like room through an open window. To start the quest, you need to talk to him. If you do this conversion, you can summon him while fighting Godrick the Grafted.
Talk with Rogier About Godrick
After defeating Godrick the Grafted, you need to talk to Rogier in Roundtable Hold. After talking to Rogier you will get his weapon.
What to do if Rogier is not talking?
If you can't talk to Rogier, you've probably completed Ranni's quest. You must not have spoken to Ranni to complete Rogier's quest.
Bloodstain at the Bottom of Stormveil Castle
After talking to Rogier, you need to interact with the bloodstain at the bottom of Stormveil Castle to continue the quest. In this bloodstain, you will see the death of a Rogier-like figure. After interacting with Bloodstain, you must return to Roundtable Hold and talk to Rogier. Rogier will tell you the story of the first demigod killed in history.
Hugging Fia
You need to let Fia hold you to advance the quest. You must hug Fia until the "Talk in secret" option appears. When you choose this option, Fia will confess to you that she is the Deathbed Companion. Then you must ask her about the Black Knifeprint. When you ask this question, you will get a map called Knifeprint Clue.
Black Knife Assassin
When you go to the location described on the map, you must defeat a boss named Black Knife Assassin. To find him, you must reach the Black Knife Catacombs in Altus Plateau. There is an illusory wall inside the Catacombs. Before fighting the Black Knife Assassin, I must say that he has a complex and powerful pattern. After defeating him, you will get an item called Black Knifeprint.
Back to the Rogier
You must deliver the Black Knifeprint to Rogier to advance the mission. Rogier is still waiting in Roundtable Hold. You can advance the quest by talking to him and giving him the Black Knifeprint. After resting on a grace, you need to talk to Rogier again to get the Black Knifeprint back.
Talk to Ranni
To advance the quest, you need to talk to Ranni the Witch in Ranni's Rise. Ranni will confess to you that he stole the Death Rune. After talking to Ranni, you should go back to Roundtable Hold and talk to Rogier. After talking to Rogier and getting the necessary information, you need to talk to Ranni again. After talking to Ranni a second time, you should return to Roundtable Hold and talk to Rogier. So you can complete the task. After speaking to Rogier for the last time, you must go back to where Rogier was. You will see that Rogier is dead and you can loot his items.