Why is Revan screaming and tearing up the common room?"
"Oh, I locked his cape in 'freshers again.
—Meetra Surik and Malak
Alek Squinquargesimus was born on the remote world of Quelii in the village of Squinquargesimus. With the devastation of his homeworld at the hands of the Mandalorian Neo-Crusaders culminating in the Battle of Quelii, Alek fled to the Galactic Republic, where he was discovered by the Jedi Order to be Force-sensitive. For this reason, he was taken to the Jedi Enclave on Dantooine and trained in the ways of the Force. It was here that he met and befriended the Jedi Guardian known as Revan.
With the escalation of the Mandalorian threat, Revan and Alek sought to convince their Jedi peers to assemble a task force to aid the Republic, a move which was decried by the Jedi Council. Eventually, with the revelation of the Mandalorian genocide on Cathar, the Council grudgingly gave Revan, Alek, and their followers, the Revanchists, permission to serve the Republic as members of the Republic Mercy Corps.
Through the use of Revan's tactical genius and Alek's inexorable wrath, the Revanchists and the Republic eliminated the Mandalorian threat in under a year, culminating in the Battle of Malachor V. With the war's end, Revan and Alek journeyed to the Unknown Region to discover the true source of the Mandalorian threat. Their minds warped by the power of the hidden Sith Emperor whose Empire dwelt far from the watchful eyes of the Jedi, they returned as Sith bent on destroying the Republic they had once vowed to defend.
Their war machine powered by the long-lost Infinite Empire Star Forge, a space station and factory powered by the Dark Side, Revan and Malak waged war on the Republic, until a last-ditch attempt to end the conflict ended with the capture of Revan by a Jedi strike force. Having betrayed his friend and master Revan by firing on his flagship during the raid, Malak seized control of the Sith Empire, and continued the conflict against the Republic.
Malak met his end at his friend's own hands aboard the Star Forge, where Revan, reprogrammed with a new identity by the Jedi Council and once again a member of the Jedi Order, struck down his old apprentice and brought an end to his own Empire.
Personality and traits
According to the Revanchist Suri Sunrunner, who had some interactions with the Guardian during the Mandalorian Wars, Alek possessed a quick wit and unique sense of humor, unlike Revan. He and his partner in crime Meetra Surik frequently played pranks on Revan, which often ended with Revan seething in rage and humiliated in front of other Revanchists. Unlike Revan, who preferred to keep some distance between himself and his followers, Alek frequently mingled with his fellow Revanchists and Republic allies, including a young Carth Onasi, who stated that he was "impressed" by Alek's character during the Wars.
Thus, his sudden, tragic fall from grace was all the more shocking to those who, like Sunrunner, had liked and admired him during the Mandalorian Wars.
A Jedi Guardian with a focus in one-handed weapon combat, Alek utilized a standard single-bladed personal lightsaber with a slightly longer hilt to account for his above-average hand size. The weapon contained a cyan color crystal as well as a Sapith focusing crystal obtained from a rare crystal cache he and Revan discovered during the Mandalorian Wars.
This weapon remained in his possession until the time of his death at Revan's hands, after which, the weapon passed into the hands of the Jedi Council. Ultimately, the weapon was claimed by the Jedi Archivist Atris during the First Jedi Purge and stored with other artifacts in her facility on Telos.
Behind the scenes
The author is a great fan of the video game Star Wars: Knights of the Old Republic, and thus elected to keep much of Malak's history and character the same for On the Nature of the Force. However, a few details about his past, character, mode of service, and relationships were changed to "humanize" him a bit more and make his fall a bit more tragic.