Giuki and his Queen and all their sons gave a great welcome to Sigurd when he came to their hall, for he looked such a one as might win the name of being the world's greatest hero. And Sigurd went to war beside the King's sons, Gunnar and Högni, and the three made great names for themselves, but Sigurd's shone high above the others.
When they came back from that war there were great rejoicings in the hall of the Nibelungs, and Sigurd's heart was filled with friendship for all the Nibelung race; he had love for the King's sons, Gunnar and Högni, and with Gunnar and Högni he swore oaths of brotherhood. Henceforward he and they would be as brethren. King Giuki had a stepson named Guttorm and he was not bound in the oath that bound Sigurd and the others in brotherhood.
After the war they had waged Sigurd spent a whole winter in the hall of the Nibelungs. His heart was full of memories of Brynhild and of longings to ride to her in the House of Flame and to take her with him to the kingdom that King Giuki would have given him. But as yet he would not go back to her, for he had sworn to give his brethren further help.
One day, as he rode by himself, he heard birds talk to each other and he knew the words they were saying. One said, "There is Sigurd who wears the wondrous helmet that he took out of Fafnir's hoard." And the other bird said, "He knows not that by that helmet he can change his shape as Fafnir changed his shape, and make him look like this creature or that creature, or this man or that man." And the third bird said, "He knows not that the helmet can do anything so wonderful for him."
He rode back to the hall of the Nibelungs, and at the supperboard he told them what he had heard the birds say. He showed them the wondrous helmet. Also he told them how he had slain Fafnir the Dragon, and of how he had won the mighty hoard for himself. His two sworn brothers who were there rejoiced that he had such wondrous possessions.
But more precious than the hoard and more wondrous than the helmet was the memory of Brynhild that he had. But of this he said no word.
Grimhild was the name of the Queen. She was the mother of Gunnar and Högni and their half-brother Guttorm. And she and the King had one daughter whose name was Gudrun. Now Grimhild was one of the wisest of women, and she knew when she looked upon him that Sigurd was the world's greatest warrior. She would have him belong to the Nibelungs, not only by the oaths of brotherhood he had sworn with Gunnar and Högni, but by other ties. And when she heard of the great hoard that was his she had greater wish and will that he should be one with the Nibelungs. She looked on the helmet of gold and on the great armring that he wore, and she made it her heart's purpose that Sigurd should wed with Gudrun, her daughter. But neither Sigurd nor the maiden Gudrun knew of Grimhild's resolve.
And the Queen, watching Sigurd closely, knew that he had a remembrance in his breast that held him from seeing Gudrun's loveliness. She had knowledge of spells and secret brews (she was of the race of Borghild whose brew had destroyed Sinfiotli's life) and she knew that she could make a potion that would destroy the memory Sigurd held.
She mixed the potion. Then one night when there was feasting in the hall of the Nibelungs, she gave the cup that held the potion into the hands of Gudrun and bade her carry it to Sigurd.
Sigurd took the cup out of the hands of the fair Nibelung maiden and he drank the potion. When he had drunk it he put the cup down and he stood amongst the feasters like a man in a dream. And like a man in a dream he went into his chamber, and for a day and a night afterwards he was silent and his mind was astray. When he rode out with Gunnar and Högni they would say to him, "What is it thou hast lost, brother?" Sigurd could not tell them. But what he had lost was all memory of Brynhild the Valkyrie in the House of Flame.