Kirk was forced to take on the role when the Klingon fleet arrived necessitating the speedy departure of the USS Enterprise - the Organians supplied him and Spock with clothing and cover stories, establishing Kirk as a leading citizen, and Spock a Vulcan trader.
The Klingons' leader Kor, son of Rynar immediately recognized a more fiery temperament in "Baroner" and appointed him his liaison to the Organian people so that he could keep an eye on a, "ram amongst the sheep". Kor's first officer Kahlor, son of Kolox initially questioned this decision, but agreed with his commander once Kor explained the tactic.
However Kor's watchfulness was not enough to prevent Kirk and Spock from sabotaging an ammunitions depot, which prompted the Organians to reveal their true identities shortly after in distaste at that violence. (TOS episode: "Errand of Mercy"; TOS comic: "Against Their Nature")
Some time later Kor used a holographic image that had been recorded of Kirk as Baroner while trying to stir up hatred in Gaius (son of Keras) as part of a long term plan to manipulate the Romulan Star Empire into war with Federation as a way to circumvent the Organian Peace Treaty. (TOS comic: "The Hollow Crown, Issue 2")