Two years after season one Sirena discovers she's pregnant with David's child. When she is kidnapped by an evil merman king who wants to make her his queen it soon becomes a race against time and the merman king's evil guards to rescue Sirena who has been brainwashed to believe her rescuers are her enemies.

In the middle of dragon raid Valka, Hiccup and Astrid are kidnapped by a dragon. Eighteen years later they are on their way to speak with Eret and his daughter Heather when Stoick is snatched by three Mysterious Vigilante Feral Dragon Riders who take him to the Snowy Bewilderbeast's nest.

After an accident Hiccup discovers he has been turned into a Night Fury. Running away into the forest he comes across a female Night Fury. Will he fall in love with the extremely beautiful female Night Fury who calls herself Sapphire or will he ignore her and try to return to Astrid and Berk or will he stay? Will they mate and leave Berk?

Heather is snatched by a Night Fury and never seen again.

Five years after Hiccup dies Astrid meets someone who claims the dead can be brought back to life. Desperate and determined to get Hiccup back Astrid agrees to revive him and prevent the dead from entering the living world. Sequel to That Fateful Day.

Hiccup is kidnapped. When they find out Hiccup is missing Astrid sends out a search party who find him lying unconscious on the western beach. After waking Hiccup up Astrid hugs him and doesn't let go. Later that night he dies scarred and terrified. Waking up Astrid gets no response from Hiccup.

Hiccup and his daughter Heather are taken by a Night Fury to the Isle Of Night. Once there they befriend and train two Night Furies, one hatchling and one grown up. Twenty years later Hiccup and Heather return to Berk on their Night Furies Toothless and Raven. Set during the time where Valka was carried off but it's Hiccup and Heather who are carried off instead.