Having spent his youth on Romulus as part of Ambassador Spock's Unification Movement, D'Tan believes that for the Romulan species to survive, it must reject the culture of secrecy and deception that has defined them for centuries.
- “Explore the Flotilla”: Romulan Republic players meet D'Tan onboard the flagship of the Romulan Republic after escaping from Virinat, where he persuades them to join his cause.
- “Turning Point”: D'Tan attends a conference on Khitomer to convince the Federation and Klingon Empire to support the establishment of the colony on New Romulus.
- “Temporal Ambassador”: In an alternate timeline, D'Tan is a laborer working for the Tholian Assembly at a base in the Azure Nebula.
- “New Romulus Aid”: The player meets with D'Tan in a cutscene upon beaming down to New Romulus. Here, D'Tan and Obisek, leader of the Reman Resistance, agree to jointly establish a new Romulan-Reman homeworld on New Romulus.
- “Hidden Camera”: D'Tan matches wits with Subcommander Khiana of the Tal Shiar.
- “Latest Findings”: D'Tan invites the player to review the latest findings of the scientists exploring New Romulus, and asks for their aid in investigating a newly-discovered underground site near an active volcano which is too dangerous for Romulan scientists to enter.
- “Secrets of the Ancients”: D'Tan joins the player in the underground site where an amazing discovery is made.
- “Surface Tension”: D'Tan is part of a Romulan delegation at a conference to discuss ownership of the Jenolan Dyson Sphere and the threat posed by the Undine. He is later present in the Great Hall on Qo'noS when the Federation and the Klingon Empire agree to put an end to their fighting in the face of greater threats.
- “Blood of Ancients”: D'Tan is evacuated from New Romulus when the planet is attacked by the Iconians and the Heralds. He is seen aboard the Romulan Flotilla when the defenders regroup after the mission.
- “The Temporal Front”: D'Tan is present at the Alliance Summit on New Romulus.
- “Storm Clouds Gather”: Together with other leaders, D'Tan travels to Deep Space 9 for an Alliance summit on the Hur'q threat. Here he expresses the Republics's reluctance to assist the Dominion in a fight against the Hur'q.
- “Home”: D'Tan is present with the other leaders on Deep Space 9, where he speaks to the player stating that he has initiated peace talks between the Karemma and the Dominion after the final battle against the Hur'q was over.
- “The Temporal Front”
- “Echoes of Light”
- “Of Signs and Portents”
- “Beyond the Nexus”
- “Melting Pot”
- “Scylla and Charybdis”
- “The Renegade's Regret”
- “The Plausibility of the Possible”
- “Impossibility of Reason”
D'Tan confronted by Subcommander Khiana in his office on New Romulus.
- Aennik Okeg - President of the United Federation of Planets.
- L'Rell - Current Chancellor of the Klingon Empire
- J'mpok - Former Chancellor of the Klingon Empire.