From a previous post, at least a few of you will know of my fervent devotion to being a Trekker.
Yea, verily, forsooth, and in veritate.
I am that ultimate fangirl.
With that disclaimer out of the way, I shall now Trek out a bit.
The Tal'Diann is Romulan Military Intelligence.
The Tal'Shiar is, or was, the Imperial Romulan Secret Police.
The two have never been on the best of terms with one another.
The Tal'Shiar has always been under the control, supposedly, of the Empress or Emperor, but in reality, the Tal'Shiar has always served the Tal'Shiar, just as Sela has always served Sela.
The Tal'Diann is the Intelligence Branch of the Romulan Military.
Tal'Shiar vs. Tal'Diann ... Spy vs. Spy.
Numerous examples from Romulan history might be provided, but in the end, the Tal'Shiar were led by a sociopathic fanatic, blinded by his devotion to the Iconians, as he ordered the destruction in Hobus, which led to the death of ch'Rihan ...
By this time, the Tal'Shiar were programmed -- conditioned, brainwashed.
Skip forward in time. The madman at the helm of the Tal'Shiar has been executed, by the Tal'Diann Fleet Admiral of the Fleet, in the presence of Obisek, New Romulus Republic Fleet Admiral of the Fleet. The Empress has been carried away by Iconians. The former Praetor Taris has been taken from a maximum security Starfleet facility by Iconians.
In the ashes, from the far-flung embers, the smoldering coals came together under the Sword of the Raptor Star, and there arose a New Romulan Republic.
Old Alliances have been renewed. New Alliances have been forged.
The Tal'Shiar remain in service to the Iconians.
The Tal'Diann remain in service to the New Romulan Republic's Military.
The Tal'Diann fleet is now working with the Orion Syndicate Intelligence Division, the Klingon Defense Forces Intelligence Branch, and disaffected Vulcans loyal to the KDF.
The Tal'Diann have made use of "the Orion Method" in espionage. A classic example is the case of none other than Riov (Commander) Di'on Charvon, the Captain of the Memenda, the lead Romulan D7 and Fleet Commander of the Romulan D7 fleet (in the TOS episode "The Enterprise Incident" -- the character was portrayed by Joanne Linville -- Joanne Linville at IMDB). On this occasion, the Orion Method did not result in immediate desirable effects, but the seed was planted, and Spock went on to spend some time Under the Raptor's Wings and eventually established the Reunification movement.
Who is to say then, that Commander Charvon's mission was a failure?
For nigh a century, the identity of this early heroine of the Tal'Diann has been obscured by now-outdated interpretations of Mnhei'sahe, due to which she changed her name, but the time has come for her identity to be rescued from obscurity, in line with D'Tan's policy of greater transparency in the Republic. She was born Di'on Charvon, the name known to history as the Riov of the D7 fleet which attempted to take the Federation flagship, a woman "disgraced" by failure and capture in this effort, a woman who nevertheless went on to perform many good works for the Tal'Diann and the Romulan people, whose "failed" mission may be better seen in hindsight than it was at the time. In fact, Riov Di'on Charvon of the ChR Memenda was none other than Liviana Charvanek, niece of the Emperor Shiarkiek and the earlier Empress Ael t'Rllaillieu, and wife of Devoras Narviat, Praetor of the Romulan Star Empire.
Riov Liviana Charvanek:
The ChR Memenda, a Klingon-manufactured K't'inga D7, Riov Charvanek's flagship: