Roshan is the baby whom Manny, Sid, and Diego try to return in Ice Age.
After Roshan is separated from his family, the three animals discover him and begin a journey to reunite him with his human father. Their mission drives the main plot and gradually changes the group from an accidental collection of companions into a protective family-like unit.
Roshan’s name is revealed in the film’s story rather than functioning as a nickname like Manny, Sid, or Diego. The baby is a human character in a world otherwise dominated by prehistoric animals, which makes his safety the emotional center of the adventure.
A common mix-up is confusing Roshan with Peaches. Peaches is Manny and Ellie’s daughter, introduced in Ice Age: Dawn of the Dinosaurs. Louis is a molehog who appears in Ice Age: Continental Drift, while Ethan is associated with Peaches in a later film.