[Aratlithiel]

I've often wondered what might have happened if any of the other Fellowship members had gone with Frodo and Sam and I believe that the addition of any one of them would have resulted in failure. No one but Frodo (not even Aragorn) had the deep, personal awareness of what the Ring could do and the all-consuming desire to see it destroyed. And no one else had the fundamental love for him that Sam did. Sam made sure Frodo got to the Cracks of Doom not because it was the right thing to do or for the salvation of Middle-earth or any other reason other than that it was what Frodo wanted and therefore, Sam was going to see it done. Sam had blind faith in Frodo and pure love. If Frodo had a goal, Sam was going to help him accomplish it, regardless of what it was - pure and simple.

Any of the other members of the Fellowship would have eventually tried to stop Frodo as they discussed doing above Rauros - whether it be out of love or pity or any other motivation. They may have even tried to take the Ring from him (albeit only to relieve him of his burden) which would have driven him mad. Of any other member of the Fellowship besides Sam, who would have understood the complexities of the situation Frodo was in and who among them would have assisted him to his doom as Sam did? No one else believed in Frodo the way Sam did, therefore, Sam - and ONLY Sam - could have played this part in the Quest.

Besides, if any one else had come along, would Gollum have played the part he did? I think it more likely that Gollum would have been prevented from accompanying them in one way or another and so not been present at the very end.