He is a minion of Jul Mdama and is nothing more than a lacky. He wears the armour of a Minor Elite, but for whatever reason he doesn't wear a helmet. Odd. Almost as if Jul himself 'borrowed' it to use as a potty and never gave it back.
Gek cannot speak a word of English and what little Sangheili he speaks is punctuated with the occasional 'Urrrrrr....' and 'Uhmmmm.....'. This makes it difficult for Gek to get the message across to prisoners, especially ones that try to run away.Gek is too stupid to wield a gun, so he carries Jul's beam rifles around instead. He gives it to Jul and then bows menially, only to be whacked later on for not attaching the scope.
Gek also lets prisoners escape really easily. When Doctor Glassman of the UNSC Infinity was captured by the Storm Covenant, Jul tried to make him fix a Forerunner device despite the fact that no-one knows how to stoop to the level of Forerunner stupidity. Despite this, Jul made Glassman wear an explosive vest and gave Gek the detonator.Despite clear instructions by Jul to Gek on how to operate the explosive, Glassman escaped when he finally managed to activate the device, and Gek didn't notice until he was out the door. Glassman met up with a SPARTAN who removed the vest and threw it into the doorway. By this time, Jul had realised that Glassman had escaped and ordered a group of Elites to find him. Gek activated the explosive, but a case of horrible timing meant that the vest blew up the Elite intercept sqaud. Gek realised his mistake and promised to slay the Humans. He tracked them using active camo and attacked, but the SPARTAN was more than a match for him and he was soon overpowered. He stepped on Glassman's arm and held him up, threatening to kill him if the SPARTAN did not stand down. So the SPARTAN shot Gek, killing him instantly. What a failure.