[Veritas]

I think you're right Thingol.
But in the Silmarillion is stated that before Sauron made the ring, he was really the antagonist, after Morgoth.
Because Sauron imbued the lion share of his power in the ring, the ring became more powerfull then Sauron himself.

Maybe we shouldn't see the ring as an isolated character, but as a part of Sauron's mind and power (just like the Valar are parts of Iluvatar's thoughts), in LOTR seperated from it's master and longing to come back.