Dairou made his first appearance in Mortal Kombat: Deception. He was once a member of the Seidan Guard and believed in the power of Order and lived by the strict codes of his superiors. He had saved many lives during his years of service, but when he attacked and killed the man whom he believed murdered his family, Dairou was arrested and sentenced to a life of incarceration.
He eventually escaped during a riot incited by the Resistance. He emerged from prison a changed man. No longer would he follow orders of the Seidan Guard. Neither could he bring himself to give in to Chaos. Instead, he opted to serve himself. He became a mercenary, a warrior for hire, and became revered in Orderealm's secret underground.
His neutrality had been put to the test, however, as his current contract was to find and kill his former fellow guardsman, Hotaru. Normally Dairou took no risks and ambushed those he had been hired to kill. But in this case, he felt compelled to announce his intentions to kill Hotaru. There still must've been some code of honor left in his cynical heart.
In Dairou's Mortal Kombat: Armageddon ending, he defeats Blaze and gains a glowing suit of armor. Shao Kahn attacks Dairou but is defeated. Dairou becomes the new ruler of Outworld, and under his rule, the realm becomes beautiful and majestic as it once was. Convinced of his peacefulness, Earthrealm and Edenia form an alliance with Outworld that would ensure peace throughout the realms, forever.
Alignment:
Alignment: Neutral
Mortal Kombat: Deception

I was once a member of the Seidan Guard, I believed in the power of Order and lived by the strict codes of my superiors. I had saved many lives during my years of service. But when I killed an assailant in a fit of rage, I was arrested and sentenced to a life of incarceration. For all the good I had done, the event that had come to define me was that one moment of Chaos. I eventually escaped during a riot incited by the Resistance.
I emerged from prison a changed man. No longer would I follow orders of the Seidan. Neither could I bring myself to give in to Chaos. Instead, I opted to serve myself. I become a mercenary, a warrior for hire, and have become revered in Orderealm's secret underground. My neutrality has been put to the test, however, as my current contract is to find and kill my former guardsman, Hotaru.
Mortal Kombat: Deception

Normally, Dairou took no risks and ambushed those he had been hired to kill. But in this case, he felt compelled to announce his intentions to kill his fellow Guardsman, Hotaru. There still must have been some code of honor left in his cynical heart.
Hotaru was defeated... but before Dairou could reveal who had commissioned the attack, Hotaru drew his dying breath.
Mortal Kombat: Armageddon

The fire of Blaze enveloped Dairou and formed around him a golden suit of armor. Enraged, Shao Kahn attacked, but the armor scorched his body with every blow. Dairou defeated the emperor and claimed Outworld for himself. Under his rule, Outworld once again became the majestic realm it had been in ages past. Convinced of his good nature, Edenia and Earthrealm forged an alliance with Dairou that would ensure peace and stability forever.