In the fellowship of the ring, Sam becomes part of the fellowship
after hearing the secret meeting of Elrond's Council.
In the two towers Sam and Frodo are met by Gollum. Sam hates Gollum, and Gollum tricks Frodo
that Sam is betraying him. Sam remains protecitve of Frodo, still, but does not trust his decison about Gollum.
In Return of the King, Sam saves Frodo in Shelob's Lair, but Sam believes Frodo is dead and
he makes the choice to take the ring and leave Frodo. But, he discovers that Frodo is still alive, so he goes to the tower
to save Frodo.
Finally, the end up at the crack of Mount Doom. Frodo destroys the ring, if it wasn't for his
faithful friend, Samwise Gamgee, he might not have gotten that far.