Smeagol, like all Ringbearers, came upon the Ring part by accident, and part by the Ring's own design.
For as you know, it was a wicked, treacherous thing, and it made Smeagol as wicked and treacherous as itself. Smeagol was one of the "River people" - the Stoors, who are sort of hobbit race whose one main distinction is the ability to grow beards, although this doesn't mean they can grow very good ones, nor do they seem to make a habit of sporting 'em. It just ain't very Hobbit-like. Leastwise, i don't think Smeagol could grow one -- leastwise not when I saw him. The Stoors do not live in the Shire, but rather to the north of it, where they conduct river trade, mostly with the Brandybucks, and are looked upon as peculiar and timid, and typically as outsiders. They never come into the Shire for shopping nor naught else, not unless they have good reason. In all my years, i never once saw any others.
Five centuries before Mr. Bilbo ever found the Ring, two Stoorish Hobbits named Smeagol and Deagol were fishing in the Anduin River when (so the story goes) the boat tipped while they tusseled with a large fish, pulling in Deagol to the bottom of the river. That was where the Ring found him. It glinted gold in the sun, and both hobbits were fascinated it. But the Ring, being what it was, instantly ensnared them both. They fought over it, and Smeagol ended up murdering his best friend and kinsman.
He fled in horror, so mr.Gandalf tells the story, and he became reclusive and secretive, using his treasure for spying and thieving until he was found out by his neighbors. He was shunned by the villagers, who laid upon him the name of "Gollum", because of a hideous gagging sound he developed in his throat. He ran off into the wilderness to fend for himself., and learned to live by his wits, to hunt like an animal, and sleep wherever he could. As the long years dragged on, the Ring took its effect as it always does. It turned him not just fearful, but vicious and spiteful as well. He lived on and on, longer than any normal Hobbit could ever hope to live, but he got nothing good out of it. He slowly transformed into an aged, hideous little monster, very old to look at, but physically strong and agile beyond what would be normal for even the strongest Hobbit.
In time, he found a crack in the side of one of the Misty Mountains, and it led him to a deep cavern where the sun and the moon could not see him, and where he thought the Ring would be kept safe and secret. By that time, he scarecely even resembled a Hobbit at all. He became a scavenger, predator, and a cannibal -- and would eat anything that came his way. He only ventured from his hiding hole when the Ring left him and grabbed hold of Mr.Bilbo Baggins instead. But Gollum needed his 'Precious' more than he needed to hide in the dark, so that need forced him to come out into the world once again.
For sixty years, Gollum hunted for mr.Bilbo, while he himself was hunted for and questioned by such people as Mr.Gandalf, Strider, legolas' father, King Thuranduil, and even the Lord of the Dark Tower hisself. But always he hunted for the Ring. He picked it up its trail again after slinking back into the south end o' the Misty Mountains, when we all passed through the Mines of Moria. He must've smelt it on Mr.Frodo, or else it was a'callin' to him in ways no one else coudl understand. So Gollum once again had to play a major part in the fate of the Ring and the Ringbearers.
I didn't feel one bit sorry for the little nasty buggar at the time, but I suppose i do now. He was, after all, a victim of the Ring. It corrupted and ruiined him, and it did so faster than it did to most. I suppose under the right conditions, it might have happened to any of us who touched the Ring. Sure enough, he was capable of doing anything at all if it would bring back the Precious to him. He persued Mr.Frodo through swamps and woods and through them Hellish wastes of Mordor, and betrayed us to a giant, ugly spider.
Mr. Frodo called it 'an irony', I call it just strange luck. Gollum in the end got his wish - to have the Ring all to himself, even though it meant his own death. But as Frodo said, 'Let us forgive him, for I could not have done this deed without him.' Well, maybe he was right. I'da just stabbed him with my sword, and then where would mr.Frodo have been? he would've ended up as the new Dark Lord, and that would have been horrid.
So a toast to Smeagol, the most unlikely Hobbit hero of all. I try to remember him much more kindly than I did when we followed him across Middle Earth."
... SAMWISE GAMGEE, ESQ.