From Halopedia, the Halo wiki
Cadmon Lasky was a junior officer of the UNSC Marine Corps trained as an Orbital Drop Shock Trooper. He was the elder son of Colonel Audrey Lasky and the brother of Captain Thomas Lasky, the future commanding officer of the UNSC Infinity. He was assigned to the 10th Shock Troops Battalion.
Cadmon was the favorite pupil of many of his instructors during his career at the Corbulo Academy of Military Science; when Thomas attended the Academy years later, he did not live up to Cadmon's reputation due to his tolerant view of the Insurrectionists. During his stay at Corbulo, Cadmon set a record for morning drills; his record remained the highest when Thomas enrolled in the academy. Cadmon graduated second in his class and it was generally believed he would pursue a career in the Office of Naval Intelligence; to the surprise of his fellow students and instructors, he joined the Marines and applied to become an ODST soon after.
During the Insurrection in either late 2525 or early 2526, Cadmon was stationed on Jericho VII for at least 131 days. While there, he received a large tattoo of the iconic "Death Head" emblem on his back. Later, he was deployed to the jungles of Arcadia, where he earned the nickname "Volcano" among his unit after drinking polluted river water and contracting diarrhea.
By the 496th day of his deployment, Cadmon was stationed on the colony world of Andesia. During a firefight with Insurrectionists lasting for seven hours, Ridge, a longtime family friend and member of Lasky's squad, was killed in action. Cadmon was deeply upset by Ridge's death, which prompted him to cut his hair out of respect for Ridge, who had stated that he would look tougher with a shaved head.
He enjoyed a close camaraderie with his brother, and the two kept regular video correspondence.
Death and legacy
The entirety of his squad was killed by Insurrectionist forces on Andesia. As there were no remains, their mother felt Thomas should not leave school to attend his brother's funeral. Cadmon's death initially upset Thomas to the point of helpless despair. However, Thomas eventually came to regard his brother's sacrifice as a source of inspiration rather than grief. Thomas then began to acclimate to his role as a future officer.
List of appearances