Trista Haddock

Trista was Stoick's older sister, who got exiled in her teenage years after her brother, Hiccup, got killed.

Unexpected
Trista attends the twins' naming ceremony, where she sneaks up on Astrid and persuades the new mom to hand her the newborn Adrianna. When Astrid declines, she forcefully takes the girl and hands her back after having a good look on her grand niece. Shortly after, Stoick recognizes her and chases her out of the Great Hall, along with Gobber and a few other men.

Family
Adrianna Haddock

Astrid Haddock

Stoick the Vast

Other
Gobber

Etymology
Trista is a female name of Welsh, English and French origins, deriving from the male name Drust, meaning "riot" or "tumult".