Flynn first meets the young Gustave while living in Gruegel. He patiently puts up with Gustave's temper and self-loathing and always remains at his side. Ever loyal, Flynn accompanies Gustave and Queen Sophie to Jade when they are relocated there.
Always being by Gustave's side means Flynn gets caught up in a lot of trouble and unnecessary circumstances, such as being kidnapped by bandits. Although Flynn has no social status at all, he still accompanies Gustave everywhere, even going so far as to gatecrash a party held by Sir Thomas, where they meet a new friend, Leslie.
It is unclear what happens to Flynn following Gustave's death. He assists Gustave in his conquest of Wide, and is last seen after he and the others find Gustave's sword at the destroyed Southern Fort. From that point on, he is no longer seen in the story.