Tug serves as the leader of the bears who live at the Salmon Run as such, he show deep care for all of the bears there, big and small. He also helps Kenai ease into the bear lifestyle.
Sometime before the events of Brother Bear, Tug apparently toppled a tree that was blocking the view from his cave; unfortunately, the tree in question was home to a family of chipmunks, which quickly took up residence in his home as retribution for the desecration of their old home.
Tug doesn't make an appearance until very late in the film. He is first seen at the Salmon Run, telling Kenai to stop screaming, as he is scaring off the fish. When Kenai says that he doesn't belong at the Salmon Run, Tug tells him that "every bear belongs here". Tug along with the other bears later tell stories to each other and listens to Koda's story about how he got sepreated from his mother.
Tug makes a brief appearance in Brother Bear 2. Kenai and Koda meet Tug, and Koda says that he and Kenai are going to Crowberry Ridge to pick some berries. When Koda starts naming the various kinds of berries that he and Kenai are going to eat, Tug slows Koda down and mentions that those are a lot of berries. Shortly after, a female bear calls for Tug, and Tug tells them that he has to go, and then leaves to be with his love interest.
Tug and his love interest later appear at the end, happily watching Kenai and Nita's wedding ceremony.