Role in the franchise
Riders of BerkDagur first appears when the Hooligan tribe is expecting an annual visit from the chief of the Berserkers, Oswald the Agreeable. But then when the Berserker ships arrive at the island, it is shown that Oswald the Agreeable's son, Dagur, has become the new chief of the Berserkers, and now has the title of Dagur the Deranged.
The visit to Berk is to renew a peace treaty between the Berserkers and the Hooligans. Dagur spends most of the time insulting his father and looking for dragons to kill, ignoring the polite demeanor of Stoick and the other vikings. Later in the episode, when Barf and Belch burst into the Great Hall, he leads the Berserkers in a hunt to catch the rogue Zippleback. Barf and Belch are brought into the arena so that Dagur and Stoick can kill them and sign the treaty in dragon's blood (which Dagur has continually requested). However, the execution is stopped by an "attack" staged by the other dragons, directed by their riders with hand signals. Dagur is forced to flee, telling Gobber the Belch to consider the treaty signed.
Defenders of Berk
Dagur reappears when the Dragon Riders are on Dragon Island for a training exercise to sharpen their stealth skills. Unfortunately, Dagur is also on the island with the goal of killing any dragon he encounters, particularly the infamous Night Fury. Due to a twist of fate, he and Hiccup 'join forces,' with Dagur even referring to Hiccup as his 'brother'.
Though the Dragon Riders try their best to hide their dragons and the fact that Berk actually trains them, Hiccup is forced to reveal the secret in order to save Toothless. This enrages Dagur, who sees this as a violation of the peace treaty. However, despite his advantage of strength and rage, Dagur is defeated by Hiccup's tactics, shield, and Toothless. He later swears revenge, but orders his men not to touch Hiccup, stating that he is going to finish them himself.
Dagur and his Berserkers then fought Hiccup and the Dragon Riders over a freshly-revived Skrill. Dagur's tribe later joins forces with Alvin the Treacherous and the Outcast Tribe in order to attack Berk. Dagur double-crosses Alvin, apparently killing him and forcing the remaining Outcasts to swear loyalty to him. However, Dagur loses the Skrill to Hiccup and is now even more determined to destroy him and capture Toothless.
He has now gained full control over the Outcasts and their Island, merging his army with theirs and increasing his military might so that his forces will be strong enough to attack Berk.
Meanwhile, the dragon riders come across Outcast Island and discover that the Berserkers are building something, but they cannot find out what it is. Thinking that it is nothing important, the teens leave the island and head for home. Later, Trader Johann returns from Outcast Island and informs Stoick that he overheard the Berserkers talking about a new weapon. Stoick relays the information to Hiccup and assumes that this weapon is what the riders saw on Outcast island. When the dragon riders return to Outcast Island they discover that the new weapon is a large catapult that fires nets to capture dragons. The Berserkers successfully use it to bring down Gustav and Fanghook, as well as Hiccup and Toothless. When Toothless is captured, Dagur attempts to kill him and Hiccup but his plans are foiled by Snotlout and Gustav and their dragons. The dragon riders leave Outcast island, and Dagur questions why his plans never seem to work. Savage suggests that it is because of Dagur's execution, to which Dagur agrees and threateningly pulls out his sword while the men cower.
Dagur then uses strategy in his attack by tricking Trader Johann into bringing a load of scrap metal to sell to Berk. However, Johann is unaware that the scrap pile is actually a Smothering Smokebreath nest, filled with hatchlings. Throughout the course of two days, the Smokebreaths steal all of Berk's metal, including weapons, leaving island vulnerable to attack. Dagur sends the Berserker armada to Berk intending to destroy the island settlement (and make Hiccup kiss his boots). However the dragon riders have learned that they can control the Smokebreaths and ruin Dagur's plans by having the Smokebreaths steal the metal that holds the ships together. The Smokebreaths do so, and the ships literally fall apart under the Berserkers' feet, leaving Dagur and Savage floating on a wooden raft. Dagur pushes Savage off into the water and declares that it is not over, before having his helmet stolen by a Smokebreath. He mutters to Hiccup, "You will kiss this boot..." and floats away.
Dagur returns with plans to capture Hiccup and the dragon riders. Together with his armada, he sneaks onto Berk and plants a dragon root in the academy. When the dragon riders (except Hiccup) try to remove the dragon root and calm their dragons down, Dagur locks them in the academy, forcing Hiccup to surrender Toothless in exchange for his friends' freedom. However, Stoick and the villagers intervene, leading to a major brawl between the Berserkers and Hooligans. During the battle, Alvin intervenes, much to Dagur's surprise. When they run out of luck, Savage suggests retreating, but Dagur, refusing to leave Berk empty-handed, captures Stoick as hostage in exchange for Toothless. He is last seen loading Stoick onto his ship.
He then had Savage deliver a message to Berk, stating that he will trade Stoick for Toothless, and that Hiccup has twenty-four hours to respond. Hiccup decides to work with Alvin, who knows the layout of Outcast Island better than anyone. The two manage to sneak past the islands' defenses, but are captured in the arena. Dagur, however, captures Toothless and imprisons Hiccup , deciding to make the Night Fury the new symbol of the Berserkers, which would involve many changes. He suggests renaming Toothless "Deathkiller," as the former name doesn't make any sense to the Berkserker chief (Toothless is always bearing his teeth at Dagur). When Alvin and Mildew release the Whispering Deaths, the Outcast Arena collapses, causing Dagur, his soldiers and Toothless to fall into the pit below. Dagur tries to get on the dragon's back, but is quickly thrown off. However, when the Screaming Death shows up, Dagur realizes why the dragon is so upset and captures its mother. Thankfully, Snotlout shows up and frees her, allowing the Whispering and Screaming Death dragons to fly off with one another, reunited. After the battle, Dagur tries to attack, but is stopped by Alvin. He is last seen being threatened and calling out to Hiccup, and it is likely that Alvin took back leadership over all of the Outcasts.
Race to the Edge
Dagur returns in Race to the Edge and serves as the main, later tertiary antagonist. About three years after his defeat by the Hairy Hooligans, the Outcasts, and the dragons, Dagur was imprisoned by Alvin, and is no longer chief of the Berserker tribe. Vorg and a few others Berserkers, including Savage, were imprisoned as well due to their loyalty. He eventually escaped and stole Johann's ship. He planned to steal the gold from Trader Johann to rebuild his army. He soon crosses paths with Hiccup and the Dragon Riders, with the former discovering the Dragon Eye. Dagur initially takes it from Hiccup, but the young Viking quickly manages to steal it back. Dagur still manages to get away with Johann's treasure.
Dagur's men manage to salvage the traps from the Reaper, but Dagur was still after the Dragon Eye. Later, they captured Gustav Lar who agrees to help Dagur get it by having Hiccup trade for Gustav. The unofficial dragon rider takes Dagur to an island using the Dragon Eye, to get the treasure. However, this was a trick, with Hiccup's help to get the Dragon Eye back. Dagur drops it into a chasm, but Gustav and Hiccup are able to get it.
It was revealed that before his imprisonment on Outcast Island, that Dagur wiped out Heather's village and her family. In a rage, she tried to kill him. Dagur immediately recognized Heather and proceed to capture her, but she and her dragon Windshear were saved by Hiccup. Dagur later planned to meet with another tribe to rig his ship with dragon proof catapults and winches, though the Dragon Riders were tipped off by Johann and set out to capture him. While Fishlegs, Snotlout, and the twins distracted Dagur, Heather and Astrid snuck aboard to take out his men. When defeated, Heather commanded Windshear to kill Dagur to avenge her family, only to be stopped by Hiccup and Toothless. Hiccup explained too Heather that her horn, which her father gave to her, was a gift from Stoick to Oswald the Agreeable for his newborn daughter. This meant that Dagur was actually Heather's brother. He attempted to ask her to join but to no avail.
Dagur then attacked Berk to lure the Dragon Riders out, then following them to find Dragon's Edge. In the process, however, he destroyed Astrid's home which inspired her to train an auxiliary team to protect Berk. The new riders assisted in defending Dragon's Edge from Dagur, forcing him to retreat.
Dagur is revealed to have joined Ryker and the Dragon Hunters, and Heather has joined him as well.He, Ryker and Heather try to get Astrid to tell them where the Dragon Eye was. Dagur tried to convince Ryker to throw the riders overboard, but Heather suggests they use them as slaves for Viggo. Dagur confronts his sister for objecting his idea, which she replies she was protecting him. That it something when wrong, Ryker would be blamed and not Dagur. Hiccup and Snotlout soon arrive and manage to free the other riders.
Dagur and Ryker appeared when they planned to kidnap Hiccup and use him find the islands the Dragon Eye had led the riders to. Once they had Hiccup, they began to sail out However, Barf & Belch witnessed Hiccup's abduction and set out to rescue him. They also sent out their distress signal to call the other riders. Dagur was about to fire multiple arrows using a large crossbow, but was blown up by the Zippleback. The hunters managed to capture Barf & Belch, but were saved by Ruffnut and Tuffnut. The Dragon Riders continued to attack the ship, forcing the hunters to retreat. Dagur was then sent on a wild goose chase by Heather to find a second Dragon Eye.
Dagur, alongside Heather, Ryker and their fleet, then attacked Dragon's Edge. Dagur then questioned Ruffnut about the Edge's defense. Despite Ruffnut's false claims, Dagur continued to try to get in Dragon's Edge to steal the Dragon Eye. After several failed attempts, Dagur realized he hadn't seen Hiccup, Snotlout, Fishlegs, or their dragons. This meant they did fall for the Hunters trick by luring Johann to an island that was home to dragon that had been attacked by the Hunters, and split up. Dagur faced off against Astrid, but was quickly overpowered by her. Hiccup and the other Riders soon arrived, along with the herd of wild dragons to protect the Edge. Dagur managed to escape with Heather and the Hunters.
During one of their runs, the Dragon Hunters spotted a storm, which Dagur immediately recognized as the Frozen Skrill from three years earlier. Determined to get it back, Dagur tells the Hunters to head towards the flashes. He was surprised that Hiccup actually brought the Skrill to them, but returned his attention back to capturing it. After taking the Skrill down with the Dragon Root arrows, Hiccup tries to grab the dragon away, but is cut off, thus returning the Skrill back in Dagur's hands. The Dragon Hunters later landed on an island to rest, while placing the Skrill in water so he couldn't shoot lightning. Knowing Hiccup would come back for the dragon, Dagur and Ryker soon captured the Dragon Riders as well. However, Hiccup manages to get to Toothless, who in turn frees the Skrill. Once free, the Skrill attacks Dagur and the Dragon Hunters, forcing them to run.
After another failed fight against the Dragon Riders, Ryker begins to suspect Heather is giving them information. However, Dagur defends his sister and threatens Ryker if he tried to hurt her. Ryker is soon given information that it time to meet up with Viggo. Heather asks Dagur what he knows of the Dragon Hunters' leader. He describes him as being the opposite of Ryker, svelte and smart, even more so than himself, which he doesn't quite believe; and that he loves the art of the kill. Dagur also tells Heather that Ryker is even afraid of Viggo, despite being the older brother. Dagur soon drops the subject and hugs Heather, happy that the two of them are together after so many years. Dagur joined Ryker and the Dragon Hunters in capturing the Flightmare.
When it is revealed Heather was a traitor, Dagur was tasked with locking her up. Heather tries to reason with her brother that they should not turn on each other. This causes Dagur to viscously question Heather about her family values when she had tried to kill him before. Heather remiss him that she didn't know he was her brother at the time, and that he destroyed her island. Seeing Heather's point, he asks if she was still mad about that. When she didn't respond, Dagur locks her up, telling her that the only one he can trust is himself. Later on, Dagur plays Maces & Talons with Viggo, using their men. While Dagur gains the upper hand, Viggo still beats him, showing his readiness to make sacrifices. After the Dragon Riders being their attack, Viggo sends Dagur off to take care of Heather. Before he does, Dagur asks Ryker why he puts up Viggo. The hunter replies that even though Viggo gets to him, he's still his brother, leaving Dagur alone to think. Dagur and two Hunters later take Heather away. However, the two men notice something is off, just before Dagur bashes their heads together, knocking them out. He then takes out his axe and uses it to free Heather from her shackles, and whistles for Windshear. Dagur then leaves, but not before looking back at his sister.
The title of Dagur the Deranged is actually quite fitting, as he is seen as violent and extremely unstable. When he laughs, his smile changes to a frown after a while. At times he performs erratic acts without thought or reason, other than to shed blood and kill. This impulsiveness makes him unpredictable. He might be hyperactive as well as insane. He is especially eager to kill dragons and sees them as nothing more than targets for his sadistic sense of pleasure. It is shown that while Dagur prides himself as a dragon killer, he has little regard for the sport, having brought his entire armada to assist him on his hunt for Toothless. He also has an enormous ego, is very rude, and disrespectful. He also is very vengeful. He also showed a lack of respect for those who were peaceful in his debut.
But inside his insane and sadistic nature, he still has some good in him. Dagur is understandably very fond of his sister, and helped her numerous times. Most iconically, he even dared to go against Viggo's orders to rescue Heather, who was sentenced to death, even though she was siding with the riders.
Role in the series