Who are Merry and Pippin in the movie?
Merry and Pippin are part of the Fellowship and at the end of ‘The Fellowship of the Ring’, they are being captured by the Uruk-Hai. In ‘The Two Towers’ Merry and Pippin escape from the Uruk-Hai by going into Fangorn forest, where they meet Treebeard. They make the Ents go to war against Isengard and they go with them.

Who are Merry and Pippin in the book?
Merry and Pippin are part of the Fellowship but they are taken captive by orcs and Uruk-Hai. They escape to Fangorn Forest and meet Treebeard. The Ents decide to go to war against Isengard and Merry and Pippin go with them.

Changes in the Two Towers
The characters of both Merry and Pippin are quite the same in the movie as they are in the book, and the emphasis in both is on their dealings with Treebeard. Neither one of the hobbits really stands out as an individual because they do almost everything together and get pretty much equal amount of time in the scenes on screen and in the book chapters. Merry’s still being the slightly smarter one and in the movie the hobbits are again more comical characters than in the book. But during The Two Towers both the movie and the book show Merry and Pippin changing from simple funny companions in the fellowship to hobbits who want to do their maybe small part, but still a part, in the big events of the world.

Captured by the Uruk-Hai
Merry and Pippin are captured by the Uruk-Hai on Amon Hen, and carried towards Isengard, to Saruman. Merry is wounded and the Uruks cure him with their medicines. Pippin drops his Lothlórien leaf from his cloak and hopes that Aragorn finds it. They stop near the Fangorn Forest and the orcs want to kill and eat the hobbits but the Uruks deny it saying that the halfings carry an elvish weapon that the master of the Uruks wants. While they are arguing, the Rohirrim attack and kill the orcs. That way the hobbits get a chance to escape to Fangorn Forest.

In the book the events of the journey are quite similar, but the pain and despair of the hobbits is shown more clearly because the journey takes many days and for a while the half-dead hobbits are forced to run themselves driven by whips. The escape is a little different because one of the orcs seems to know about the Ring and Pippin acts like he has it so the orc would take them aside to search them. Then the Rohirrim attack and the hobbits can escape to Fangorn.

Here Merry and Pippin are left all by themselves. There is no Gandalf, Aragorn or even Frodo to tell what to do. They start to realize the seriousness of the situation; that this is not just a fun trip with friends through Middle-Earth. In the movie Merry says: “We might have made a mistake leaving the Shire, Pippin.” In the book Pippin says: “I whish Gandalf had never persuaded Elrond to let us come.” The hobbits now have only each others and they have to hold together and become more of a team to survive.

Treebeard
Treebeard captures the hobbits in Fangorn when they are escaping from a hungry orc. He takes them to see the White Wizard who will tell if they are hobbits or something else. It’s not shown here but later it’s revealed that the White Wizard was Gandalf. In the book Treebeard finds the hobbits on a hill and takes them directly to his home, so the hobbits don’t meet Gandalf until the company of King Théoden arrives in Isengard after the Battle of Helms Deep.

When they are in Fangorn Forest, a quite light scene shows Merry and Pippin drinking the Ent-draught and Merry wonders if Pippin is taller than before. Pippin is also making funny Ent-like sounds. In the book they drink Ent-water many times but it happens only in plain eating/drinking purpose without any comical side and the possible growing is not mentioned until later by Legolas.
After that Merry and Pippin are captured by a willow tree and Treebeard comes and commands the tree to release them. This doesn’t happen in the book while they are in Fangorn, but that happens in chapter 1.VI. The Old Forest where they are caught inside Old Man WillowTom Bombadil rescues them.

In Fangorn Treebeard becomes kind of the safe figure to Merry and Pippin and he gives them some comfort being old and wise, but he still remains somewhat distant and mysterious to the hobbits. The hobbits are never really afraid of Treebeard, only interested in him and his tales. For Treebeard the hobbits are strange beings such as he has never seen before but still interesting and their coming kind of reminds him about the world there is outside Fangorn.
In the book the relationship between Treebeard and the hobbits is pretty much the same. The hobbits seem closer to him because they spend more time together while visiting Treebeard’s Ent-house and they also get to know another Ent, Quickbeam. During their stay in Fangorn they hear a lot of interesting stories about the Ents, the Entwives, the Elves and Saruman.

Entmoot
These scenes were extended in the movie to show how Merry and Pippin have realized the seriousness of the events. The decision of the Entmoot is that the Ents can’t hold this storm and that they won’t take part in the war. Merry isn’t happy about that and tries to change their minds but Pippin is still thinking that what could they do anyway and wants to go home. But Merry has now understood the bigger picture and says: “The fires of Isengard will spread, they will burn the woods of Tookborough and Buckland. And all that was once great and good in this world will be gone. There won’t be a Shire Pippin.” That is probably what makes Pippin understand, because when Treebeard is taking them out of the forest to go home, Pippin comes up with an idea that they want to go home from south, near Isengard. There Treebeard sees how Saruman has destroyed a big part of the forest so dear to him. He gets so angry that he calls the Ents with a terrible cry to go to war against Saruman. We see how the Ents destroy Isengard and Merry and Pippin bravely sit on Treebeards shoulders killing orcs by throwing stones towards them.

In the book the result of the Entmoot is that the Ents will go to war against Saruman and the hobbits just decide to go with them but the destruction is not described. Only later the hobbits tell Aragorn and others what happened at Isengard. The actual change in the hobbits also isn’t clearly described in the book. They just agree when Treebeard says that he takes them along to the war. Maybe it’s just everything they have heard from Treebeard and his words that the hobbits may be even able to help him and also their friends out there, that makes them come along.

Flotsam & Jetsam
After the destruction of Isengard Merry and Pippin stand in Isengard, knee-deep in water, making fun of Saruman and wondering where to get something to eat. They find Saruman’s food storage room, along with leaf from the Southfarthing and start a cosy chat, smoking pipeweed. The hobbits’ part in this movie ends here and the next events in the book are at least partly shown in the Return of the King movie.

When the Battle of Helms Deep is over, Théoden and part of the Rohirrim, Gandalf, Aragorn and the others find the hobbits resting on the walls of Isengard. Then Gandalf and Théoden ride to meet Treebeard while Merry, Pippin, Aragorn, Legolas and Gimli spend some time eating, smoking and telling their stories. Here the hobbits describe how the destruction of Isengard happened. Both in the book and in the movie these moments after the battle are pretty easy-going for the hobbits and for a while they can be just plain carefree hobbits again enjoying eating and drinking.

The Voice of Saruman and the Palantír
The whole company goes to see Saruman and Pippin finds a dark crystal globe thrown down from Orthanc by Gríma Wormtongue. Gandalf hurriedly takes the ball away from him and the whole company begins their ride away from Isengard towards Edoras. When they take a brake to rest, Pippin is feeling restless and can’t sleep because his wondering about the crystal globe. He can’t help but take it from Gandalf and look into it. He suffers a great trauma and wakes up Gandalf and everyone by his cry. Here Gandalf tells that the ball is a Palantír and by looking into it, as dangerous as it was, Pippin might have given them some time to use while the enemy is confused. So Gandalf takes Pippin and they leave to ride directly to Minas Tirith. The short carefree time for the hobbits is now over and the paths of Merry and Pippin are parted.