The One Ring was destroyed. He had watched the one he had been sent to Middle-earth to cast down rise a last time in the moment of defeat, and had spared Sauron, who he had once called by other names, and even brother, a last moment of sorrow mingled with contempt. Two weary hobbits had seemingly ended Sauron's existence with the flick of a wrist, the spinning of a small circlet of unholy metal into the fire from which it came.
Mairon, Sauron, Annatar, Artano, Aulendil, Gorthaur, all the names his brother had hoarded in his long life, had amounted to so much dust, reflected the wizard who had gathered not a few names himself. Sauron the Fool! Even a cat does not leave the pantry when the mice are at large. At the end of so many Ages, Sauron had grown only in arrogance, leaving Orodruin unguarded, to his ruin.
Now, hours after their Enemy's fall and the saving of Frodo and Sam, Sauron's onetime brother sat by the fire, blowing rings of smoke from his pipe. Around him, the victorious armies of the West drank, told tales, stood on watch, and dozed. He had delivered the Ring-bearers into Aragorn's healing hands, and watched as Pippin, too, was tended by the returned King. There was no more that he could do for them.
For the first time in two thousand mortal years, the wizard sat purposeless, his old shoulders lightened of their heavy burden. It felt strange to have no course left but the path to the West. Narya lay quietly on his finger; its fires cooled. His own power slept, like Ulmo's waves at low tide.
Come home, Olórin; the wind seemed to sigh. He would revel, make farewells, and obey; for Gandalf was needed here no more.
Author's Notes (on the matter of Sauron's names):
Papers that JRRT compiled in the 1960's have yielded an original name for Sauron, used before the Maia gave his allegiance to Melkor - that of Mairon, which means "the Admirable" or "the Admirable One". This information was published in Parma Eldalamberon #17, p. 183; and was unearthed for me by Nath, via the HASA Research Forum.
Annatar (meaning "Lord of Gifts"), Artano ("high-smith"), and Aulendil ('one who devotedly serves the Vala Aule') are names that Sauron used during his Second Age sojourn under false pretenses with the Jewel-Smiths of Eregion, according to Note #7, The History of Galadriel and Celeborn, Unfinished Tales. According to The Silmarillion, the Elves also called Sauron Gorthaur (the Cruel).
Thanx also to Elena Tiriel, tireless lore-seeker (and lore-master) of HASA.