During the "What's in a Name?" quest in "Divinity 2: Ego Draconis" you are given hints that Erlking, Laiken's Goblin servant, may know something about the Demon connected to Laiken's soul. When you meet Erlking, you realise that discovering the Demon's name is not as easy as simply asking Erlking, because he is mute. Fortunately, there are other ways of getting information from someone in this game, even if they can't speak.
Read Erlking's mind. He's mute, so you have no other way of getting information from him. Engage your mindreading ability and he will be thinking of a specific book.
Walk to Erlking's bookshelf and interact with it to pull up a list of books. Scroll through the list and pick the book that he was thinking of, "Gothe's Ballads," and read it. This opens up a secret area in Erlking's library.
Go into the secret area, where you will discover a chest, but it is locked. If you have not been to the third floor of the Battle Tower, go there now, using the elevator from Erlking's library.
Explore the third floor until you find an Abomination Master. Kill him to get his key, then return to the library.
Enter the secret room and unlock the chest with the Abomination Master's key. You will receive the Soul Forge Contract, which contains the Demon's name.