- Born 100 ABY on Kuat into the immensely rich Veryn family, a dynasty in steep political decline.
- Recruited at 13 into Krayt's One Sith by Darth Kato, a Krayt operative on Kuat, who recognized his potential.
- From his recruitment until 135 ABY, Haerminous Veryn served as Kato's acolyte and apprentice. Veryn and his master serve the One Sith by hunting down ancient Sith and Jedi artifacts for Darth Wyyrlok
, who is secretly seeking a cure for Krayt. Veryn becomes fascinated with Sith history and the potential uses of the Dark Side, and harbors doubts about the authenticity of Krayt's Order. He is elevated to Darth in 134, and takes the name Callidus.
- 138 ABY, amid the dissolution of the Sith Empire, Callidus flees Coruscant to Hutt Space where he abandons his Sith name and begins to ingratiate himself with several Hutt Clans as a dependable mercenary and assassin.
- In 140 ABY, Kato tracks Callidus down to punish his apprentice for cowardice. In the ensuing combat, Callidus slays his former master, but not before learning from him the location of Darth Wyyrlok's defeat of Darth Anddedu's spirit.
- Over the next decade, while working for the Hutts as a bounty hunter, Callidus tracks down Darth Anddedu's ruined holocron in his tomb, and rebuilds it. He learns the secret of transfer essence
from Andeddu, among other many dark secrets.
- Callidus spends 147-153 ABY as an assassin for the Hutt Grand Council, while secretly in tutelage to the holocron of Anddedu and building a collection of Sith artifacts. In his travels, he comes across the rare book of dark side philosophy, the Analects
of Symnod Dratha. From Anddedu and Dratha, Callidus comes to see the error of Krayt's ambitions, and abandons dreams of political power in favor of total dedication of Force mastery.
- Over time, Callidus reestablishes contact with the wider Sith Order, in hopes of gaining more artifacts. Callidus meets Darth Ruine, and is impressed with his ruthlessness and committment to reforming the Sith, though he finds Ruine's fanaticism for causing galactic chaos distasteful.
- 160 ABY Callidus takes on his first apprentice, Darth Karios, and the two begin planning the formation of the Dratha Magi. By 173 ABY, Callidus has formed a small circle of disaffected Sith and Jedi followers which he names the Dratha Magi and cuts of ties with the wider Sith. The Dratha operate out of Hutt Space but maintain a low profile.
- Darth Ruine approaches Callidus and proposes an alliance.
- Callidus and the Dratha participate in the purging of the Sith, ruthlessly killing those deemed weak or unworthy and pillaging their libraries and wealth. After the purge, Callidus and his minions retreat back to Hutt Space and use their new wealth to form the Veryn Farspace Trading Guild. Callidus abandons his guise as an assassin and adopts his old name, Haerminous Veryn, a wealthy merchant lord who approaches the Hutts asking to become their vassal. Over the next two decades he ingratiates himself with the Hutts and becomes a considerable powerbroker in clan politics, frequently serving the Grand Council as a foreign diplomat.
- Callidus transfers his spirit to a clone body for the first time, abandoning his aging original form. Wary of the dangers and excruciating pain of this dark practice, he begins seeking the writings of Darth Pelagius to find a less costly form of immortality.
- The Dratha take over an old Scythe-class battleship from pirates, and outfit it to serve as a base of operations. The ship is renamed the Wolf Queen
- Ruine's promises of vast rewards from the Jedi library lure Callidus into joining his fellow Sith Lords in an attack on the Jedi on Tython. Darth Callidus pillaged the Jedi library shamelessly after the Church-Sith combined assault, and just as shamelessly fled back with his followers to his hidden fastness in Hutt Space after he had taken what he wanted. This earned him the nickname Lord Snake from many of his fellow Sith.
- Callidus is shocked by the Church's attack on the Sith, thinking Ruine was more than a match for a bunch of ambitious clerics. The Dratha Order weathers the storm relatively well in its isolation, and begins to indirectly aid the Sith in their struggle agains the Church.
- Callidus, frightened, begins casting about for allies against the Church and forms an agreement with Muito Poder.