|Spoiler warning: this article or section may contain major plot or ending details! Proceed with caution.|
Flint as he appears in Mother 3
|Appears in||Mother 3|
|First chapter||Chapter 1|
|Non-PSI ability||Brute Force|
In Mother 3
In Chapter 1, he first appears waiting for his family to come back from their vacation in the mountains; however, the forest is on fire, and Thomas demands that he helps with getting Lighter and Fuel out safely. He later also assists with finding his family in the mountains and forest.
When Hinawa is discovered to be dead, he is sent into a state of shock and depression. He becomes obsessed with her, and spends most of his time afterwards offering flowers for her and visiting her grave. Later, when Claus goes missing, he also spends a large amount of time searching for him in the mountains. He continues doing this for over three years.
Due to his obsessions with Hinawa and Claus, he ends up spending little time with Lucas over the next three years. However, he does give him his old Courage Badge as a good luck charm, albeit indirectly by telling Nippolyte to give it to Lucas the next time he sees him.
Flint finally discovers the Masked Man's identity in Chapter 8. He tries to communicate with the Masked Man during the final battle, but is severely injured by the Masked Man's usage of PK Love Ω twice. After the battle, he asks Lucas to forgive his "hasty brother" and to pull the seventh and last needle.
Many fans have theorized that there is a connection between Flint and Ness, due in large part to Flint having possessed the Courage Badge. Shigesato Itoi explained that this was intentionally left open-ended, so that players who thought there was a connection "could go on thinking it if they liked." 
- Nindori.com interview with Shigesato Itoi, translated