The characters and setting of Lord of The Rings belongs to the Tolkien estate, and Elric of Melnibone belongs to Michael Moorcock.
Aragorn, Gandalf, and Elric rode in silence as they returned from the ruins, a mad sorcerer had tried to do something that Aragorn wasn't entirely certain he understood beyond trying to revive the Witch King. Elric had been roped into this quest shortly after he had arrived and met the party of three, making it a party of four.
Aragorn thought of the young soldier that had fought with them, and how he had been slain during the battle by Elric's sword, Stormbringer, the Black Blade which was at his side and murmuring in its scabbard cold. Gandalf had not been particularly pleased to see Elric when they met him, but he was a decent ally.
"I do believe this is where you leave us, Sir Elric." said Gandalf as he took a puff from his pipe. Elric nodded.
"I believe so wizard." confirmed Elric as he unsheathed his blade and uttered strange words. A portal appeared, as he rode into the portal, Elric turned to face Aragorn.
"Farewell friend, for you were a thousand times more virtuous than I."
With those words, the albino left.