[Gordis]

Originally Posted by Groin Redbeard

I think Frodo took pity on Gollum because he could relate to the burden that Gollum carried for so long

Indeed, Frodo was in unique position to understand Gollum - he could do it better than anyone else in ME. He knew exactly how Gollum felt, why he couldn't give up the Ring and was horrified seeing the end result of the ring-addiction.
If you forgive me this lame analogy, Frodo is like a person just starting using drugs who sees another totally wrecked by them - but still he cannot stop. He cannot drop the Ring and go away not only because he has promised to carry out the Quest and save Middle-Earth, but also because he has no strength left to do it, even if he wished to. It is the road with no return - and even the destruction of the Ring is no cure for him.

No taste of food, no feel of water, no sound of wind, no memory of tree or grass or flower, no image of moon or star are left to me. I am naked in the dark, Sam, and there is no veil between me and the wheel of fire. I begin to see it even with my waking eyes, and all else fades.

He can't help feeling mental kinship with Gollum.

Groin: ...but Sam was naturally suspicious of Gollum.

He was suspicious of right about everyone they met, but his beloved Elves: Strider, Boromir, Faramir, and Gollum. It was a usual narrow-minded mistrust of strangers/foreigners so common in the Shire + his over-possessiveness towards Frodo. Remember, he had suspected Aragorn almost all the way to Rivendell, at least before they met Glorfindel. Maybe it was a good thing, as Frodo seems a bit too trusting, at least at the beginning. What if instead of Aragorn they had met Saruman's or Sauron's agent in disguise?

Groin: but Frodo surely had to have some relationship with Sam if they were going to travel together.

Sure, they had a strong relationship involving trust and affection, but it was hardly friendship. As I said, it was more like a master-dog thing, but not quite. Such relationships are all but extinct nowadays, but in Middle-ages they seemed to be quite common, and are often met in English literature (Walter Scott etc.).

Groin The Ring is what he wants, but he can't make up his mind whether to let the evil thing go and have long lasting happiness or hold onto it and be happy for the moment.

I don't think Gollum had any choice. He certainly had NO strength left to let the Ring go after 500 years with it. Even Frodo had none. And how could he hope for "long lasting happiness" if the destruction of the ring literally meant his death? Strange that he still had some good feelings left...