Commander Kragnar served as First Officer of the U.S.S. Maximillian NCC-74997 under his sister, Captain S'Quid Tai Septaric.

Kragnar was as typical a Klingon as you could get.  Warlike, and obsessed with honor.  However, he was also a strong follower of the ancient ways, and a firm believer in the bonds of family.  It was this that brought him back to the family when his mother was dying, and what led him to swear an oath to her to follow her sister and protect her whenever possible.  Therefore when she was chosen to leave the Klingon Empire and enter the Federation exchange program, he had no choice but to follow.  He settled in with her on the Maximillian, and quickly rose to a position of Chief of Security, and later First Officer.  Where S'Quid was a rarity for a Klingon, soft-spoken and prefering to let diplomacy move things forward, Kragnar was her big stick, acting forcefully to defend her and the ship's honor.  

When the Maximillian encountered the Marconian vessel, he initially challenged her honor, but later repented to her.  After her subsequent death, he came very close to challenging Admiral Robert Lyon, but from her memory, backed down at the last moment.  After the destruction of the vessel, Kragnar returned to the Klingon Empire, the last surviving member of the Septaric house.