Brigadier Kerla was a 23rd century Klingon, in service to the Klingon Empire as a Klingon Defense Force flag officer who was a supporter of General Chang, and military adviser to the Klingon High Council in the early 2290s decade.
He was appointed to the position shortly after the Klingon Civil War of the year 2292, and Chang was instrumental in appointing Kerla over Chancellor Gorkon's preferred candidate, Torlek. (TOS video game: Klingon Academy)
This was merely a ruse however, in order to gain her trust and persuade her to go to war with the United Federation of Planets when she eventually took over as Chancellor herself. (TOS novel: The Fearful Summons)
In 2293, Kerla accompanied Gorkon, Azetbur and Chang to a diplomatic meeting with James T. Kirk and Spock. During a dinner shortly after the initial meeting, Kerla made clear his opposition to the idea of peace with the Federation. Following Gorkon's assassination, Kerla retained his position under Azetbur, and along with Chang tried to push for outright war with the Federation. Azetbur resisted however, and continued with the peace talks. Kerla accompanied her to the peace talks at Camp Khitomer, though was powerless to continue the plot after Chang's Bird-of-Prey was destroyed and Patrick West's attempt to assassinate the Federation President was foiled. (TOS movie, novelization & comic adaptation: The Undiscovered Country)
In the months that followed, it emerged that Kerla had been fully complicit with Chang's conspiracy, and was its highest-ranking member still alive within the Empire. Azetbur was infuriated that Kerla had been complicit in the death of her father, in addition to manipulating her feelings, and had no hesitation in ordering that he be put to a slow, brutal death, something which happened within a year of the Khitomer conference. (TOS novel: The Fearful Summons)