B'vat was a Klingon Captain of the I.K.V. Quv by the year 2265. His house had a feud with the House of Duras during that period of time following the death of his brother due to "Duras treachery", and engaged the player at Drozana Station (mistaking it for a House of Duras ship due to a holographic disguise). His ship was nearly destroyed following an attempt to ram the player's ship.
In 2270, B'vat encountered his future-self who had come back in time to escape the player through the Guardian of Forever. He was on board the I.K.S. Worvig, a Klingon Raptor from the future, with his future-self and a number of future Klingons (Klingons with ridges on their foreheads as opposed to early 23rd Century Klingons). He remained on the bridge where he encountered the player, and his away team, before answering some much needed questions for the player involving Ambassador B'vat's plan in 2409. He was allowed to leave for a nearby Klingon vessel and requested he be given an honorable death.
In 2393, 6 years after the destruction of Romulus, J'mpok emerged as Chancellor and is accused of dishonorably killing Martok. Martok's son, Drex, made this accusation, in which B'vat, the Arbiter of Succession, rejected his claim.
By 2409, B'vat was an Admiral and an Ambassador. He was behind the surprise attack on Regulus IV, where Miral Paris was stationed. B'vat engaged the player and a fellow Ambassador before escaping and claiming to the player they will meet again. B'vat soon set about his plans involving the Doomsday Machine still left in deep space for over 140 years, a trap in the Briar Patch for the player to fall into, recruiting Amar Singh (who wanted to create a master race using Klingon, Augment and Gorn DNA) and attempting to find a way to time travel to manipulate the timeline in favor of the Klingon Empire. He discovered the Guardian of Forever in the Gateway System and kidnapped Miral Paris from the U.S.S. Kirk, who was believed to be the Kuvah'Magh (the saviour of the Klingon Empire). He then took her, and a number of Klingons, back in time to 2270 (with the I.K.S. Worvig, a Klingon Raptor from 2409) where he contacted his past-self to assist him in destroying the Federation, starting with the U.S.S. Enterprise. B'vat's plan nearly succeeded, until the player intervened and discovered the reason behind B'vat's actions. B'vat then fought the player and his away team, trying to defend his captured prisoner Miral Paris, before being killed in battle.