Si-Di-Ri was a Tiss'shar of the male persuasion. In 0 ABY, he held the position of President of the Tiss'sharl League on the planet of Tiss'sharl. Approximately eight months into that year, Darth Vader, the Supreme Commander of the Galactic Empire, visited Si-Di-Ri and the League, which functioned as Tiss'sharl's governing body. Vader compelled them to reduce the prices of TaggeCo blaster cartridges sold to the Empire. After an assassination attempt on Si-Di-Ri failed, the Dark Lord exploited the President to draw out a representative from the Alliance to Restore the Republic, as Si-Di-Ri was in discussions with the Alliance due to the Empire's price reduction demands. Upon realizing Vader's manipulation, Si-Di-Ri came to the understanding that everyone, including a president, is ultimately beholden to a higher authority. Subsequently, he stepped down from his role as the leader of the Tiss'sharl League.
Si-Di-Ri, a male Tiss'shar, had achieved the rank of President of the Tiss'sharl League, which served as the planetary government of Tiss'sharl, by 0 ABY. This was during the time of the Galactic Civil War between the Galactic Empire and the Alliance to Restore the Republic. On Tiss'sharl, politics were frequently influenced by assassinations, which Si-Di-Ri used to his advantage to ascend to the presidency. Despite this, he maintained a friendly relationship with Vice President Astre-De-Kay. Although the League was aligned with the Empire, Si-Di-Ri secretly sympathized with the Alliance and provided them with Tiss'shar technology through Timi Rotramel, a Mon Calamari senator and Rebel representative. Approximately eight months into 0 ABY, amidst a series of assassinations within the Tiss'sharl League, Darth Vader, the Supreme Commander of the Imperial forces, arrived on Tiss'sharl along with the planet's new Imperial Liaison, Demmings. When Si-Di-Ri's personal chef, who was preparing dinner for the two groups, expressed concern that Vader would not be eating, the President reprimanded him in the presence of the Dark Lord.
President Si-Di-Ri was present at the dinner, accompanied by other League members such as Vice President Geor-Dan-Thi. Geor-Dan-Thi had quickly climbed the ranks due to a string of assassinations that cleared the path for his ascent, including the death of Astre-De-Kay and other Tiss'shar. During the dinner, Lord Vader introduced Moff Giiedt's replacement, Commander Demmings, and demanded that the League reduce the prices of the TaggeCo blaster cartridges they exclusively sold to the Empire, a demand he had made twice before that year. Vader granted them a day to comply and stipulated that Si-Di-Ri should not be harmed or targeted for lowering the prices.
Later that night, while on the balcony of his residence, Si-Di-Ri was attacked by a Tiss'shar assassin. He was shot in the shoulder, but his guards managed to repel the attacker. The next morning, Si-Di-Ri left his residence alone and was briefly stopped at the doorway by a Tiss'shar who inquired about his destination. Si-Di-Ri then proceeded to a meeting with Rotramel, who was now a former senator after the Empire had disbanded the Imperial Senate. Rotramel offered to establish an Alliance base on Tiss'sharl and protect the planet from the Empire to safeguard Tiss'sharl's economy, though Si-Di-Ri questioned the practicality of this proposal.
Vader interrupted the meeting, having been informed of the President's departure by the Tiss'shar who had questioned Si-Di-Ri earlier, and killed Rotramel. Although the cyborg warlord had hoped for more significant Rebel prey, such as Princess Leia Organa, Lord Vader commended President Si-Di-Ri for delivering the Alliance representative to him. He allowed Si-Di-Ri to maintain the current price for the blaster cartridges, as the price reduction was intended to force Si-Di-Ri to engage with the Alliance, thus drawing a representative to Tiss'sharl. Subsequently, Si-Di-Ri realized that despite his rise to the top of Tiss'shar society, there would always be a greater power manipulating events and that his loyalty to the Empire might be questioned. He made the unusual decision to resign as president, announcing his intention to the other members of the League. Geor-Dan-Thi succeeded him in the role.
Si-Di-Ri, a gold-skinned Tiss'shar with orange eyes, was a skilled financier who ascended to the presidency, aided by political assassinations. He was knowledgeable about his planet's political landscape and concerned about Geor-Dan-Thi's rise. Despite the Tiss'sharl League's allegiance to the Galactic Empire, Si-Di-Ri secretly sympathized with the Alliance and supplied them with Tiss'shar technology through Rotramel. Following the assassinations and the attempt on his life, Si-Di-Ri began to feel that his well-being was temporary and wondered if the League had always been rife with assassinations.
Although Darth Vader warned the other Tiss'shar in the League that no repercussions for the price reduction should target the President, Si-Di-Ri knew the Sith Lord's promise was unreliable, as betrayal was common in both the Empire and the League. The President also felt tainted simply by having seen the Dark Lord of the Sith. The encounter with Vader and the death of Rotramel led to Si-Di-Ri's resignation, as he realized that regardless of his political achievements, a greater power would always be in control. Another reason for his resignation was his uncertainty about maintaining the facade of loyalty to the Empire.
Si-Di-Ri's first appearance was in Empire 31, a comic book from Dark Horse written by Scott Allie and illustrated by Joe Corroney, published in 2005. He later received an entry in The Complete Star Wars Encyclopedia, released in 2008.