- “Just be patient, Kenai. When you live by your totem... you will.”
Sitka loves his younger brothers and would do anything for them, the movie begins with Kenai's coming of age ceremony where each tribe member receives an animal totem which represents their personalities and he happens to be a bear, which he hates because they steal food from them and Denahi teases him for it, angering him. Sitka then tells Kenai of his own ceremony and how his totem is the eagle, which represents leadership and guidance. Moments later, they find that a bear has stolen some fish from them because Kenai didn't secure the ropes on the basket and he recklessly goes after the bear. Sitka and Denahi follow him to make sure he doesn't end up getting killed.
Kenai is knocked to the ground and Denahi defends him, but the bear knocks the spear out of his hands and it looks like it's over for them when Sitka, deciding there is no other option, stabs the ice around the bear with his spear, causing the ice to crack and break off, causing the bear to fall with him. Kenai and Denahi search for him, but only find his coat and his spirit assumes the form of a bald eagle
Later that night, a funeral is held for Sitka, and Kenai is enraged that the bear lived while Sitka died. Holding the bear responsible for what happened, so he goes out to kill it to avenge Sitka. After a battle which he succeeds, a bald eagle appears and morphs into Sitka in an ethereal form. He then approaches Kenai and is very disappointed in his brother's actions. Feeling it wasn't necessary for Kenai to kill the bear because he (Sitka) willingly gave his life to protect his brothers, Sitka punishes Kenai by turning him into a bear.
Thinking the bear killed Kenai, Denahi decides to avenge his death and tracks him down. Kenai manages to escape and meets the deceased bear's cub, Koda. Kenai finds Koda annoying at first, but eventually grows to love him and feels guilty after learning that he is the son of the bear he killed.
At the end of the movie, upon seeing Kenai nearly give his life for Koda, Sitka decides to change him back into a human and visits him and Denahi in his human form. Knowing that Koda is motherless because of him, Kenai wishes to be a bear again and stay with Koda. Sitka turns Kenai back into a bear and hugs both of his brothers goodbye, then he and Koda's mother (who briefly reunites with Koda) return to the afterlife.
He does make a cameo in his eagle form near the end of Brother Bear 2 when the Great Spirits transform Nita into a bear so she can be with Kenai and Koda (mainly Kenai).
- Most of the characters are named after actual places in Alaska, where the story is set. Sitka is named after a big city in said state.
- Sitka's spirit, in the form of an eagle, can be seen throughout the movie after Kenai is changed into a bear.
- After Kenai first wakes up as a bear, an eagle sitting on a tree branch watches him, then flies off.
- When Kenai and Koda are riding on the mammoth's tusks, after Koda says "I always wanted a brother," the camera moves upward to reveal an eagle sitting on a tree branch, watching the bears.
- When Kenai and Koda are going through the "lava path", after Koda and Kenai walk offscreen (before Koda scares Kenai), an eagle flies after them.
- An eagle meets up with Denahi in the mountains.