Mongoose Publishing's Babylon 5 RPG game has released a Drakh Sourcebook.
The Drakh may have some kind of group mind as Drakh can communicate with other Drakh over long distances. They appear to regard the name "Drakh" as both a collective name and a personal one. In "Lines of Communication" their emissary interrupted Forrell before he could utter Delenn's name, dismissing it as "unimportant." On the other hand, they're familiar enough with the notion of individual names to recognize Delenn's once it was spoken.
Keepers burrow deep into the neurological systems of the hosts. While the outer part of the host can be removed, there is always an interior part of the Keeper that would grow back quickly as seen in "Racing Mars". The only known way to do so would be to either force or kill the Drakh that spawned the Keeper; if the Drakh is killed, the Keeper will also die.
Keepers can be affected by the state of its victim. If the host drinks enough alcohol, it has been demonstrated that the Keeper would fall asleep and the host would regain control of him or herself for a short period of time (albeit in an intoxicated state). If the host's life becomes endangered, the Keeper's life is just as endangered.
When the Shadows decided to leave the galaxy to join the other First Ones, the Drakh were left behind on Z'ha'dum until the planet's destruction. When Lyta Alexander triggered the planet's self destruct systems, the planet was destroyed. Shortly before the explosion, a large fleet of ships was seen leaving Z'ha'dum by John Sheridan and his colleagues aboard the White Star. They did not know it was the Drakh.
Soon, the Drakh began attacking other races, especially those who had fought against the Shadows. They had also begun seeking out contacts among other races. One contact they made was with a member of the Minbari religious caste, who was unhappy with the turn of events on the homeworld, and offered their services in return for a homeworld of their own. When the Drakh had found out Delenn, one of the people most responsible for the downfall of their masters, was aboard, the Drakh opened fire on the Minbari ships, and managed to destroy one of the Whitestar class ships before they entered Hyperspace. However, the Minbari in a matter of seconds jumped back into the fight, guns blazing, annihilating the Drakh mothership and its attendant vessels.
Due to the reemergence of the Drakh in galactic affairs, John Sheridan convinced several worlds to allow the White Star fleet and the Rangers to patrol the borders of the various worlds. This helped reduce attacks on shipping, and also laid the foundations for what would eventually become the Interstellar Alliance.
In the year following the founding of the Interstellar Alliance, ships from Alliance member worlds began to find themselves under attack. At first, no one knew who was behind the attack, as the attackers left no survivors. But the Alliance soon discovered that Centauri vessels were behind the attack. What they did not know was that these ships were under remote control, and that most of the Centauri government did not even know about these ships. The Alliance then blockaded Centauri Prime space. The Centauri fought back against the Alliance, which eventually led to several races attacking Centauri Prime. The Alliance imposed heavy sanctions against the Centauri.
During the Alliance attack, the Drakh decided to replace the Regent with Londo Mollari. They forced Londo to consent to having a Keeper attached to him; otherwise they would have detonated fusion bombs on that world. They then killed the Regent. They also forced Mollari to give John Sheridan and Delenn a gift for their unborn baby - an urn with a Keeper buried in the base.
Over the next 16 years, the Drakh molded the Centauri into an instrument to be used in their vengeance against the Alliance. When Sheridan's son David turned 16 Minbari years old, they gave him the urn.
Sheridan and Delenn soon arrived on Centauri Prime to rescue their son. They were captured by Centauri forces. Ambassador Vir Cotto blew up the Tower of Power, the main Drakh installation on that world - revealing the presence of the Drakh to all. Despite the Drakh killing millions of Centauri, Londo decided to stop cooperating with the Drakh. In a deal to secure the freedom of the Centauri people, Londo released Sheridan, David, and Delenn. In order to prevent his Keeper from informing the Drakh of the family's escape, he then asks G'Kar to kill him. However, while G'Kar was strangling Londo, his Keeper awakened and forced him to fight back. The two strangle each other to death--fulfilling Londo's death dream.
The Drakh abandoned Centauri Prime a short time later. The Alliance, realizing the Drakh played them for fools, joined forces with the Centauri in finding the Drakh and making sure they were no longer a threat to the galaxy. The Alliance also helped the newly proclaimed Emperor Vir Cotto in rebuilding Centauri Prime.
About five years after the founding of the Interstellar Alliance, the Drakh released a deadly plague on Earth. The plague did not cause instant death, and it was estimated that it would take five years to kill all life on Earth. It was eventually discovered that the plague was designed by the Shadows and when the Drakh deployed it on Earth, it was not properly adjusted to Earth's biology. This forced the plague to take time to adapt before it could wipe out the population on Earth. Eventually, due to the efforts of the Excalibur and others, a cure was found for the plague.
The Advanced Destroyer group (Omega-class warships equipped with Shadow bio-armor and advanced beam weapons) appeared to use beam weapons that were highly similar to Drakh beam weapons.