Siro was born into the Vallaido pirate clan and grew up aboard their flagship, the Valla's Glorious Gesture. Like all Vallaido children, he began his pirate career operating the ship's turbolasers. He was trained in elements of starship operation and eventually was given command of his own boarding vessel. During his second boarding action, he attacked a transport belonging to Gorbu Dalo, a Hutt crime lord. Siro killed four people with his vibro-ax and this was the first time that he saw death so closely. He realized that he didn't have the stomach for piracy and no longer wanted to participate in it.
He used his share of the Vallaido wealth to modify and old freighter and he began racing it against other people's ships, betting their ships against his. Eventually, he was approached by Pann Tefilous, a former captain and gambler who had recently began a series of illegal starship races. Siro joined in with them and, even though the races were illegal, he soon became rich and famous.
The Sevilles, a rival pirate group to the Vallaidos, made an alliance with the Galactic Empire and their combined forces attacked and devastated the Vallaido fleet. Simito responded to this by joining the Rebel Alliance. He began operating in the Rayter sector and used the starship races as cover to deliver information for the Alliance.
One such race he participated in during this time was the Dahvil-Fodro Hyperspace Promenade. The race began on Dahvil and while walking through the crowds in the race's staging area, he made a clandestine transfer of a to some Alliance agents. The agents posed as a holovid crew from Ord Dorlass, asking about Simito's supposed feud with Seeg, a rival racer. Simito pretended to be angry and swung his vibro-axe at their droidcam, slicing off the . The data module had been hidden in his axe and secretly passed into the droid when he did this; and afterward, the Rebel agents ran off with it. Simito held his axe up above his head and the crowd cheered him.
On the next stage of the race, Simito traveled to Ord Dorlass. He and Seeg wanted to give the holovid's something to report, so they staged a fight in a large nightclub in the planet's capital city. The Rodian accidentally broke Simito's nose, so he responded by "accidentally" throwing Seeg over the bar. They were imprisoned for this, but were released the next morning and Tefilous informed them that their popularity on Ord Dorlass had increased by six points.
The next part of the race took Simito to Tintel. The next stop after that was Azna but rather than go straight there, Simito flew to Fait d'Fait to make a delivery. He docked in the warehouse of Gevil Flan and while Flan knew who Simito was and that he should have been going to Azna, he didn't say anything because he knew who Simito's family were. He changed into plain clothing, swapped his axe for a plainer model and went to the lobby of a cheap hotel, to meet with his Alliance contact. The contact was an hour late, which Simito knew would make him a lot more behind in the race. Just as he left the hotel, he was accosted by a Barabel mugger. The Barabel demanded that Simito give him his vibro-axe and all of his credits. Rather than just blast the Barabel, he pretended to act like a "screaming lunatic" and gave the Barabel his axe, before scaring the reptilian away with his shouting. He then ran back to his ship and left.
He arrived at Azna the following day and Seeg had beaten him there by two hours, so mocked Simito in a friendly way in front of a large crows. He punched the Rodian in the snout, then held his axe above his head and walked away while the crowd cheered him. He left on the next leg of the race, to Fodro, and reduced the efficiency of his hyperdrive to 75%. This would let Seeg beat him, which he found irritating, but he needed to make a lot of deliveries during the next race, so he planned to explain to the holovid reporters that his worsening performance was due to hyperdrive problems.
Simito was very helpful and extremely friendly. However, he was capable of using violent force if needed, although he preferred to use his reputation and appearance to intimidate people. Despite leaving the Vallaido pirates, he remained loyal to them and his loyalty to them was greater than that he had to the Alliance.
Simito owned a modified GAT-12 Skipray Blastboat, called Axe. He also used a gold-detailed Galinolo XiX blaster pistol and a vibro-ax, which he had decorated with red and yellow vorun feathers. He liked to wear brightly colored clothes and expensive jewelry.
- Cracken's Rebel Operatives