For part of his childhood, Allun lived among the Travellers with his Rin mother and Traveller father. When he was ten years old, however, his father was killed in the War of the Plains and his mother chose to return with him to Rin to live. Unfortunately for Allun, his Traveller heritage resulted in teasing from other children, as anything or anyone considered an 'oddity' was looked down upon, even by adults. As he grew up Allun formed a 'goofball mask' to hide his true feelings from others. He also refused to learn how to swim, not wanting to be teased even more for lacking that skill, as Rinfolk were taught how to swim as very young children.
Allun is one of the adults who choose to go up the Mountain to try and restore the stream. He is kinder and more understanding toward Rowan than the general Rin villager, due to his Traveller heritage and his own experience of being an outsider. In the swamp he sees a vision of his mother trapped in the mud, and panics and runs towards the mud, thinking that she is in danger and needs him. Strong Jonn manages to hold him back, but it is Marlie's cries for help that snap him out of it (she is trying to pull Bronden out of the mud but is in danger of sinking) and he quickly comes to her rescue. Later he admits to her that she is the reason that he was able to clear his mind and free himself from the illusion.
After Bronden and Val leave their party, Allun, Jonn, Marlie and Rowan go on by themselves. Marlie asks Allun to sing and tell tales to keep their spirits up, and he obliges her. Rowan notes that Allun seems much more at ease when Bronden, Val and Ellis are not there.
Allun is revealed to not be able to swim, preventing him from passing an important obstacle, and is forced to leave their party. He waits for them at the entrance to the cave, and when Marlie comes out returns with her to Rin. Before returning they gather some Mountain Berries which Allun found to take back with them.