Major Vaughan's command squad, callsign Sunray 1-1, is the lead element of Boomerang Company, the UNSC's most elite force of Orbital Drop Shock Troopers [though that's what they all say].
Designated Marksman.
Sparks is the squad sniper, and something of a wildcard even among the Spirit of Fire's impressively large cast of misfits and rogues. Sparks' long list of non—judicial punishments and reprimands would have landed him a full—time billet in the ship's brig were it not for two unique qualities: his unparalleled skill with a SRS-99 anti-materiel rifle, and supernatural ability to acquire the rarest [and tastiest] meal packs on the ship. Luckily, Helljumpers value good chow and a good shot more than adherence to UNSC regulations, which keeps this "Lance Criminal" from behind bars—so far.
Sparks provides fire support for the command squad with his sniper rifle and assists Turpin by designating priority targets for her drone. He also contributes to the squad's morale with his vast knowledge of terrible jokes and patently ridiculous [but completely true] "war stories" from his civilian days.