Introduced as a mechanic at the Department of Death, Glottis is a spirit of the land whose purpose in life is to drive things (he becomes very sick if he is unable to do so) - and loves to be able to do so. His other joy is being able to tinker with vehicles, but the Department of Death don't really let him do so, and he's too big to drive the cars he works on. After Manny Calavera, a reaper sorts this out with a faked work order, Glottis takes Manny to a mass poisoning where Manny finds a good soul - and that is the beginning of their friendship.
Glottis is Manny's driver and constant companion on his four year trip to find Mercedes Colomar, the one that got away, and endures some fairly rough trials - at one point this involves losing his heart for a while. He normally ends up taking a job alongside Manny in whatever way he is spending his time in waiting for Meche to arrive, as well as customizing their vehicles. At the Calavera club, for instance, he plays the piano and tries his best to keep his fiery passion away from his most addictive vice, gambling.
He is very emotional. It is also established that he's very uncomfortable when one of his vehicles comes in danger of some kind; he seems genuinely distressed at Manny's jokes about the booby-trapped Bone Wagon becoming the Blown Wagon, for instance.
Glottis proclaims that since he's a spirit of the land he can't ever leave the Land of the Dead when Manny intends to take him onto the Number Nine Express train to 'save him'. Glottis, however, explains that he has no need of saving, having a new life, job and friends, which suits him just fine.