Hiccup and Toothless remain close in Dragons: Riders of Berk, with Hiccup once even planning to leave Berk with Toothless after Mildew convinced the other Vikings that Toothless- as the 'unholy offspring of lightning and death'- was angering Thor and causing various lightning storms (It was eventually revealed to be a metal statue and perches attracting the lightning). He practically never leaves Hiccup's side. They sleep in the same room and are often seen doing even simple tasks together. The two of them easily dominated the dragon events in the Thawfest games. Toothless appears to be rather a leader among the dragons.The only occasion where Toothless has defied Hiccup was when a Whispering Death that Toothless had fought in the past came to Berk, with Toothless attempting to fight his old foe on his own- even ordering the other dragons to stay away from him during the fight-, although he eventually accepted Hiccup's aid when Hiccup deliberately jumped off a cliff while Toothless was being attacked on the other side, forcing Toothless to save Hiccup and accept his help or let Hiccup die to continue his vendetta. When he, Snotlout, and Hiccup become stranded on Outcast island, he is behind Hiccup one hundred percent even during the many arguments between the boys. He also manages to work together with Snotlout in order to save his captured rider. Toothless is also a central character, along with Hiccup and Mildew, in the season finale of Riders of Berk. He and Hiccup go off looking for more Night Furies. At first Toothless seems only slightly interested, but as they get closer and closer to their goal, both Toothless and H
Hiccup become extremely excited. Unfortunately it is a trap set by Alvin and Mildew, and both Hiccup and Toothless are captured. Toothless is locked into a high security cell in the Outcast dragon containment area. He proves his intelligence -yet again when he escapes on his own. He fools the Outcasts into thinking that he is unconscious and sick. The Outcasts remove the muzzle from his mouth, and he immediately blasts them back and frees himself. For the rest of the episode he looks for Hiccup in Outcast Island. Outcasts are on his trail, but he anhiliates them with his fire blast. This is notably more violent than he usually is with humans, but he is obviously more concerned, Hiccup is missing, and he is not going to hold back at all until he finds his owner. Toothless and Hiccup eventually find each other using dragon calls. They then both decide to attack Alvin when he appears and openly mocks Hiccup. Both boy and dragon usually refrain from "going for the kill", but Alvin has gone too far, and they dive for him. It is yet another trap, and they are both temporarily captured by bolas. The other teens' dragons swoop in and rescue them. Back in Berk, Toothless does look slightly saddened to see that the Isle of Night was fake, but both he and Hiccup agree that there is nothing wrong with being one of a kind. The season ends with Toothless and Hiccup flying off into the horizon, confident that they will be there for each other in the battles that are yet to come.
While Night Furies are nocturnal, Toothless is shown mostly active during the day, likely due to his relationship with the human characters and adapted to their schedules.