Buddy is a silent blue rat who is Surly's best friend and loyal partner in crime in all his schemes, including raiding the nut store to gather enough nuts for winter. He ends up saying his first words in the whole film 'Best Friend' to his fallen friend, believing him to have died, before happily giving him a hug, which Surly returns with a smile.
- It is unknown if he was abandoned or separated from his family when a young Surly, whom he described as 'the tiniest little rat, couldn't have been a few weeks old' saw him hanging on for dear life and rescued him from being blown away by a hurricane, and he returned the favor by rescuing Surly, forming their brotherly like bond.
- Despite never leaving Surly's side, especially when he began treating him badly when they grew up, the only time he ever did leave Surly's side was when an angry Surly hurt his feelings by calling him useless and he separated with himself to stay with the team. However they have made amends by the end and Surly begins to respect him again.
- Buddy was always thought to be mute due to never speaking a word but when he believes his best friend died, a heartbroken Buddy sadly calls him 'Best Friend'. Implying that he can indeed talk but chooses not to for unknown reasons.
- While Buddy is loyal to Surly, Buddy has also found friends in other animals such as Andie, the Bruisers, the rest of the park community and even Precious, who may have been the only animal to hear Buddy speak due to bringing the rat to the squirrel after the fight over the falls with Raccoon.
- Out of the duo, Buddy is the luckiest one, due to never having anything hurt him or anything bad happen to him, until the day Surly's reckless antics caused the rat to fall into a coma, luckily he was revived by Precious and holds no grudge against his friend's actions.
- When Andie discovers that Surly is alive, she embraces him and Buddy looks on with a big smile on his face, as if he is proud that his friend has finally earned someone else's trust and love by turning over a new leaf.
- Since Surly's change of heart, Buddy began being seen as a lovable goofball and a cherished little brother figure in Surly's eyes and Buddy sees Surly as a heroic, cool and caring big brother figure.