Grum seems likely to be a trusted personal guard. He is assumed to be a very old and powerful ogre because magic wouldn't effect him. Grum, unlike most ogres, is smart, decisive, restrained, quick and is savvy. He could shape-shift thoroughly and quickly from human-looking to Ogre. Most Ogres can neutralize magic to some degree—Grum can ground it completely.
In the seriesEdit
In Summer Knight, Harry Dresden fought him in Ronald Reuel's apartment while trying to take a photo of Reuel with some kids. Dresden snatched the photo before Grum left. Dresden thought over how Grum is different from most Ogres and concluded that he was probably a trusted personal guard.
Right after Karrin Murphy emptied her Colt 1911 gun into the Tigress, Grum attacked Dresden and Murphy at Wal-Mart surrounded by Mind Fog. Grum trapped Dresden in the garden center by bending the iron gate using a plastic bag. He awaited Dresden and Murphy when they escaped outside. While Dresden fought him, Murphy got him from behind with a chainsaw hamstringing him, he fell to the ground and crawled after her. Dresden sprayed him with gasoline in the face and back, then burned him with Sterno—regular fire, instead of spell-fire. Grum thrashed and screams and then vanished into Faerie.
After visiting Mother Summer and Mother Winter in their cottage, Dresden was ambushed by Grum who came out from a veils with Elaine Mallory behind him. When Dresden came to, Mother Winter's Unraveling was taken and he was held prisoner within Aurora's toadstool circle. Dresden told Grum that he could drop the Grum-glamour and return to being Lord Talos. And, so could the black unicorn revert to being Korrick. Lloyd Slate and Elaine were also there. Aurora admitted to sending Grum and the Chlorofiend to kill Dresden. For more, see...