Massimo, serving under the command of Mirith Sinn and Sish Sadeet as a lieutenant within the New Republic, was stationed on Phaeda after the defeat of the cloned Emperor. Ultimately, he turned against Sinn, betraying her to Grappa the Hutt. As a "reward" for this treachery, he was intended as a sacrifice to the Zanibar. However, Kir Kanos, an Emperor's Royal Guardsman, rescued Mirith Sinn, leaving Massimo behind to face his doom. Left with horrifying scars after Kanos's departure, Massimo vowed vengeance, but Kanos eventually brought about his demise.
Massimo's decision to join the Rebellion was not driven by genuine desire, but by the pressing need to escape a concealed and troubled history. He sought a new world to call home. After becoming entangled in the conflict with the Galactic Empire, he resolved to make the most of his circumstances.
When Kir Kanos, the former Emperor's Royal Guardsman, arrived on Phaeda and connected with Sinn through Tem Merkon, Massimo initially harbored doubts about Kanos's trustworthiness, given his allegiance to the deceased Palpatine.
Before Sinn accepted Kanos after he almost single-handedly saved them from the forces of Colonel Shev, Massimo made threats to usurp Sinn's command. Sinn challenged him, questioning whether such an action would distinguish him from the Galactic Empire they were opposing.
Despite Massimo's suspicion that Kanos was the traitor who had informed Shev of their location, the actual culprit was Merkon. Upon Merkon's return to Sinn's base after secretly meeting with Carnor Jax, Massimo took his life.
Following the arrival of General Wedge Antilles aboard the Lusankya, Kanos departed for Yinchorr, anticipating Jax's pursuit. Sinn and Sadeet followed suit, intending to support Kanos in his battle against Jax, leaving Massimo in charge of operations on Phaeda.
While on the Lusankya, Massimo confessed to Antilles his earlier ambition to replace Sinn, expressing his heartfelt apologies and newfound dedication to Sinn and the New Republic.
However, during Mirith Sinn's infiltration of Grappa the Hutt's court on Genon, Massimo betrayed both her and the New Republic by revealing to Grappa that Sinn was spying. As a reward, Grappa handed over both Massimo and Mirith to Zzzanmxl and the Zanibar.
The Zanibar transported Massimo and Mirith Sinn to Xo, the Zanibar homeworld, where they intended to sacrifice the two in a bizarre ritual. Though presumed dead, Massimo actually managed to escape his fate when a stray blaster bolt struck his prisoner rack during Kanos's escape from Zzzanmx. The falling rack caused Massimo to fall onto hot coals. Suffering from burns and scars, he replaced his right arm and half of his face with cybernetics.
Driven by a thirst for revenge, he attempted to assassinate Kanos by enticing the former guardsman into a trap. He bribed a magistrate to place a false bounty on Kanos's head. When Kanos arrived at Massimo's stronghold, he faced an attack from security droids, but he successfully evaded them and killed Massimo.
Peter Thoemke provided his voice for the character in the audio drama version of Crimson Empire.