Siro is a man with a strong sense of duty, discipline and honor, and an amazing fighter. He comes from a long line of protectors and takes his job of guarding Jen quite seriously. Content to follow in the footsteps of his father and his father before him, Siro enjoys his place in life and the order and security it affords him. Some have called him straight-laced, but Siro thinks of himself as - reliable.
He met Baron Reyland, owner of the city trading post, and was hired as the bodyguard for his daughter, Jen. In his line of duty, he meets Kung Lao, Jen’s lover, and Taja, a thief who was caught trying to rob them and was pressed into the Baron's servitude. Siro was fired and banished after he failed to prevent Kung Lao from seeing Jen. In his banishment, he encounters a beggar who is actually the thunder god Raiden in disguise, who warned him that Jen was in danger.
As Siro returned to the trading post and found Kung Lao and Taja, the trio is ambushed by Baron Reyland and his guards. In the melee, Takeda, Siro's replacement, kills the Baron, takes Jen hostage and reveals he is actually Scorpion, sent by Shang Tsung to kill Kung Lao. Scorpion attacks the group and is defeated, but not before he kills Jen. Siro, feeling responsible for her death, aligns himself with Kung Lao and Taja to train new heroes to protect the world from evil. Throughout the series Siro is considered the more lighthearted character of the three, but also a hard-headed one. While most of the fights in the show were won by Kung Lao, Siro often becomes frustrated and even goes so far as to slay two mystical warriors that would have given him great power as told by the fortunetellers Kiri and Ankha. Kiri ended up tricking Siro into releasing her own personal warrior, Noob Saibot, who is eventually defeated by the three. By the end of the series Siro is shown to be killed by Shao Kahn's warriors, but due to the show's cancellation it is unknown if any of them are really dead.
- Siro has a little brother name Cassar who is also a fighter; he appeared in Episode 11, Thicker Than Blood.