As a tiny child, Karn was found in Bleak by the leader of the Thieves Guild. He knows nothing about his parents or his hometown. Karn is not interested in his past, however, but dedicated to acquiring the best thieving skills. Karn is always practicing his craft. The guild leader wonders when he should tell Karn the truth about his beginnings.
In the first game he is a team member found in the prison in Auria. His hometown is Bleak. He is good at picking locks and is needed for the mission in the Thief's Tomb.
He appears in Breath of Fire II living with Bo (also from the first game). Their island is slightly NW of the first Shaman's house and players need Grandpa the whale to reach the area. The area is good for training.
As a thief, Karn has the ability to pick locks and disarm traps. Karn can also learn how to fuse with his allies which turns him and his ally into a more powerful character that have access to some of their skills like Bo's ability to hunt and walk through forests, and Ox's ability to move heavy objects. His final Fusion form gives him access to the ability to open doors with its cry.
Karn is a well rounded fighter with high boosts in Agility and a nice even boost in all of his other stats. He is one of the fastest characters in the game and can hold his own in combat. Karn's true strength lies in his ability to use Fusion to combine with other party members into extremely powerful forms. In fact, Karn's fusions make him into the best frontline fighter for most of the game as his fuson forms give him huge stat boosts and pump up his HP to near maxed levels by end game. These forms do take more damage than most party members but the big HP boost mitigates this weakness. Karn's fusion forms are largely optional in the game as they are only needed to obtain many of the game's hidden secrets and are never required in the plot. Still, it is in the player's best interest to seek out the master's who teach Karn his Fusion forms.
Karn may be a shaman as he has the power to fuse with his allies.
His hobby is acquiring shoes
Karn is the only playable black character in the series but his skin color was changed for the American version and was made to make him look caucasian. This change was probably made because his character design is reminiscent of blackface.
Karn's North American incarnation resembles Arsène Lupin III, another famous fictional thief.