Johann came to Berk and was surprised to see that the inhabitants of Berk had made peace with the dragons. He also inadvertently gave Mildew a batch of Blue Oleander flowers, which were poisonous to dragons in exchange for some of his cabbage. He also traded a botany book to Fishlegs in exchange for a necklace made of dragon teeth.
Johann then found a toy that Valka had made for Hiccup and sent word to Stoick. However, he tried to make up for lost time and lost his ship while travelling through the bog. He was then found by Hiccup and his riders. Snotlout, Ruffnut and Tuffnut were tasked with flying Johann to Berk, but instead, they left him on a small sea stack in the middle of nowhere. When Johann and his ship were finally brought to Berk, Stoick asked if there was anything he could do for Johann besides having the ship repaired. Johann angrily requested five minutes alone with Snotlout, Ruffnut, and Tuffnut.
Johann made his third appearance when he went to Outcast Island. Stoick saw his ship while searching for Hiccup, and asked for his help to trick the Outcasts. When his ship reaches the shores of Outcast Island, the Outcasts immediately board the ship and start trading. Johann then opens a trapdoor on his ship, and Stoick, Gobber, and the gang start attacking the Outcasts. They manage to defeat them with Johann's help.
Johann was briefly mentioned by Stoick. He informed the dragon riders that Johann had overheard the Berserker leader saying that he planned to test a new weapon soon. However, it turned out Dagur had leaked the information on purpose to lure and trap Hiccup and Toothless.
Hiccup brought Johann to Berk after his ship was stuck in the ice. When they got back, the entire village was empty after the Speed Stinger invasion. He helped Fishlegs and Hiccup bring a paralyzed Meatlug to the cove where the tribe was hiding. Hiccup and Toothless later brought Johann back to his ship when the frozen sea thawed and gave Hiccup a bottle of squid ink as thanks.
When Johann went to Berk to trade his wares, he sold Gobber a pile of metal from an undisclosed location. Shortly afterwards, the village of Berk was plagued with a metal thief every night. When Hiccup figured out it was Smothering Smokebreaths and suspected Johann's metal, Johann initially wouldn't confess due to customer confidentiality but was threatened by Stoick, and told them he got it from a Berserker at Breakneck Bog for a great price. Hiccup tells him it was from a Smothering Smokebreath nest and the metal had eggs, but Johann simply states he is sorry. Hiccup and Stoick leave angered and Toothless interrupts Johann before following them. At the end of the episode, to make up for knowingly giving them metal from the suspicious Berserkers and not warning them, they force Johann to sail his ship full of the scrap metal to lure the smothering Smokebreaths away, much to his chagrin and despite his pleas.
Three years later, Johann had his ship stolen by Dagur the Deranged during his escape from Outcast Island. He was then found by Ruffnut, Tuffnut, and their dragon Barf and Belch near Bucket and Mulch's ship. Johann then told the riders about Dagur's escape and the theft of his ship. He also told the riders about where he hid his treasure in the Ship's Graveyard and warned them about a heavily booby-trapped ship known as The Reaper.
Johann then had dealings with Heather and her Razorwhip, Windshear, to act as her informant on the ships that need to be raided. Hiccup confronted Johann about this, and even though the trader had sworn to secrecy, he told Hiccup that Heather's village was attacked and had been returning stolen goods to victims who had similar experiences. And that Heather was now going after the man who wiped out her island and family: Dagur the Deranged.
Johann met up with Heather at her campsite, who was with Astrid. Johann was relieved to see her, as he tried to send her a message and found her site was empty, fearing the worst. He then proceeds to tell the girls that Dagur planned to purchase dragon-proof catapults and winches. When Astrid asks if Johann is coming, he points out he's not one to ride into battle on a dragon.
Johann was briefly mentioned by Astrid. She informed the other dragon riders that Johann had seen Ryker Grimborn, Heather the Dragon Hunters at the Northern Markets buying all the cold weather gear they could in a hurry. Based on this information, Hiccup realizes the Hunters are after the Snow Wraith to get a key fro the Dragon Eye However it turned out Astrid was lying and the information actually came from Heather, not Johann.Scardian. They soon attack the Riders and make off with Fishlegs. While tracking them down, the three find it strange how aggressive the dragons were. Johann admits a bit of a relief when they started attacking the Riders over him. They soon find the pack surrounding Fishlegs on their island. Johann and Snotlout think about just leaving him, but Hiccup has a plan to save their friend.
The three work together with Johann riding Meatlug to distract the sentries. However, the Gronckle hears her rider's voice and comes flying to him, ruining the plan. Hiccup, Johann, and Snotlout are forced to retreat. After talking with Fishlegs, Hiccup explains that the rogue pack had been attacked by the Dragon Hunters, thus explaining their hostile nature. He comes up with another plan to lure as many of the wild dragons, including their leader, away so Johann and Snotlout can grab Fishlegs. They all soon reunite, along with the dragon pack after Hiccup showed them they were not the enemy with his flightsuit. Ruffnut, while riding on Windshear, finds them and tells them the Dragon Hunters are attacking Dragon's Edge. The Riders and wild dragons team up and chase the Hunters away. After the battle, Hiccup and the gang take the pack back to their island, leaving Johann alone with Smidvarg.
Johann then sent a message to Hiccup to thank him for the rescue.
Johann stole information from a pair of Dragon Hunters on Outcast Island. He then took Sir "Ulgerthorpe" and his valet to the Dragon Auction on Dragon Hunter Island. He also "brought" Viggo Grimborn and his brother Ryker dragons to be sold at the auction while stowing Hiccup and the other Dragon Riders in secret.
Johann arrives on Dragon's Edge to deliver a package to Hiccup as he and the other dragon riders deal with the volcano on their island. While their Johann bought all of Tuffnut and Ruffnut's stuff, who were preparing to leave.
Johann sends a message to the Riders that he needs their help in the Northern Markets. Johann tells them several traders and their wears except him have recently gone missing so the Riders decide to investigate. It is eventually discovered that a Sandbuster was responsible and thanks Hiccup for closing the beach where it lives so trade can resume. Johann tries to buy a sword Snoutlout wields which is revealed to be Viggo’s but Snotlout says no and Johann says goodbye to the Riders.
Johann meets up with Heather at the end of the episode revealing that he knows a man who has seen her father alive, unknown to her he is luring her into a trap.
Johann accompanies Heather as she goes to meet him and tells her the man she seeks is a Viking named Harek in a tavern and insists he stay behind as he is not welcome. Johann is startled to see Snotlout behind him and he tells Snontlout about covering for Heather. Johann notices the rare chicken feed Snotlout is holding and commends how pure it is and that if Snotlout went to Johann he could've gotten a better deal. Johann then suspects something is wrong and they rescue Heather, who is under attack by Krogan and his hunters. They flee with Krogan and his Dragon Flyers in pursuit. Johann and Heather fall off Windshear and Snotlout catches both of them and retreat after the Flyers capture Windshear.
It was later revealed in this episode that Johann had been working with the Dragon Hunters secretly all along, in order to get a specific Dragon Eye lens that was unexpectedly on Heather's belt the whole time, without the riders knowing.
When the lens doesn't reveal the location of the King of Dragons, Johann is furious until Viggo realizes that they need the lenses of the five different dragon classes in order for the Dragon Eye to show the location. Krogan suggests dispatching his Flyers to search for more lenses, which Viggo sees as a waste of resources. Johann tells Krogan to send out the Flyers and asks what Viggo's idea is. Viggo suggests stealing Hiccup's collection of lenses, which Johann forms a plan to do so.
Johann goes to the Edge and offers to get the jewels Hiccup needs for his own Dragon Eye in a few months. Hiccup refuses, saying that it would be too long so Johann suggests the Northern Markets and Hiccup agrees, despite the danger. Hiccup brings the Dragon Eye with him and the lenses after Johann suggests it. Ruff and Tuff accompany them to look for a gift for Chicken's birthday, despite Johann's protests. Johann diverts the twins away and lures Hiccup into a trap and demand he hand over his collection of lenses. The twins arrive just in time and begin to suspect there is a traitor among them, but Hiccup dismisses their theory much to Johann's relief.
After acquiring more jewels, they notice more Hunters and Flyers patrolling the markets, so Johann leads Hiccup to the Sandbuster's lair in search of the two remaining jewels. Johann suggests sending Toothless to guard the entrance while they are searching and Hiccup supposedly does so. After finding them, Johann reveals his true nature and that he is paying Krogan and Viggo to help him find the King of Dragons and become the most wealthy man in the world. When Johann asks him why he is not surprised, Hiccup explains how he already figured out who was the traitor thanks to the twins' thinking. He then said that everything made sense since it was Johann who suggested bringing the lenses and several other instances when the Riders were in danger. After a brief battle, Johann manages to escape without the lenses while Hiccup confronted the Sandbuster.
After Stoick hears of Johann's deception he orders the Berkians to destroy everything Johann gave them because they can't trust the source. As a result, Hiccup sends three traders to replace their supplies. When Stoick realizes none of them has what they need to make medicine for Gothi, he states he doesn't trust them and leaves with Hiccup to look for it himself and leaves Gobber to pick which trader they will use. It is later revealed that Stoick mistrust was well founded as all three traders were sent by Johann without Willow Bark, which is needed for medicine, to get the leaders off the island so Krogan and his Dragon Flyers can attack Berk. Stoick and Hiccup figure this out and lead the Berkians in driving the Flyers and traders away while keeping all the supplies the traders left behind.
Krogan was dispatched by Johann to retrieve a Dragon Eye Lens from an Armorwing, which was a success.
Ruff and Tuff hear a rumor at the Northern Markets that Johann knows where the Riders hid their Dragon Lenses, which turns out to be true after Krogan and his Flyers attack Wingmaiden Island.
In this episode, Johann betrayed Viggo and took over the Dragon Hunters. Viggo attempted to take his revenge with Hiccup and Toothless by his side. Viggo was wounded by Johann's Hunters and sacrificed his life for Hiccup and Toothless to escape.
As the Hunters and Flyers set course for Dramillion Island, Johann reveals to himself that he intend to have the King of Dragons to himself and have Krogan’s head stuck on a spike when he is finished.
Johann tries to capture the King of the Dragons with Krogan and some of Dragon Hunters, but in the end he got frozen by the Berserker Bewilderbeast and most likely froze to death, while trying to kill Hiccup by trying to make him fall down into the icy cliff.
Johann was added to School of Dragons to trade produce for money. When Icestorm Island came, he was carrying a Groncicle egg, which exploded and damaged his ship beyond repair in a coat of ice. It is revealed that he and Skulder the Archaeologist were partners where Skulder would find and trade artifacts from his discoveries.
In Rise of the Stormheart, Johann explains to the player that his ship was taken over by ruffians and that there was a package that contained gears for Hiccup's Dragon Eye project. Once the player finds and defeats Nikora's robots, it is revealed that it was a ship Johann sold to Harald Forkbeard, and the package on it belonged to his employer.
Johann has been added to Rise of Berk. In the game, he gathers items needed for collections and trades them a certain amount of wood, fish, or runes. These items can be used towards gaining Battle, Exotic, or even Legendary dragons. During the release of Dreadfall in 2017, Johann has a special "Speed Sale" item to offer the player.