The Two Towers Theme of Loyalty

There is a huge difference in The Two Towers between loyalty on the Good Side and loyalty (or the total lack of it) on the Bad Side. Loyalty keeps the good people in this book together. But because the people on the Bad Side are, by definition, untrustworthy, they cannot be loyal to each other. Of course Saruman is going to betray Sauron at the first opportunity he gets, because Sauron would not hesitate to hurt Saruman if it could earn him some advantage. That's the problem with being evil: you can't rely on any of your friends.

1. Both Frodo and Théoden grant mercy to characters who may, technically, not deserve it: Gollum and Wormtongue respectively. Does this mercy result in gratitude or loyalty from these characters? Why or why not? What does Gollum and Wormtongue's response to mercy suggest about their characters?
2. To whom or to what is Frodo loyal? How do Frodo's loyalties influence his decisions in The Two Towers? 
3. How does Sam demonstrate his loyalty to Frodo in front of other characters? Are there times when Sam's loyalty to Frodo becomes a problem for Frodo's quest? Why or why not? 
4. How do the characters maintain their loyalty now that the Fellowship has split up?

Boromir's final act of making peace with Aragorn before he passes away is an example of true loyalty, which is the central virtue of the moral of The Two Towers.

The disloyalty among the orcs of Isengard and Mordor just goes to show: Sauron can't triumph, because his troops are always looking out for number one—themselves.