Originally, Scrug was just an ordinary scorpion living in the Gorge of Eternal Depth until Chi dropped by Laval caused him and other scorpions to evolve along with the spiders and bats, and they gained an intense hunger for more Chi. They captured Crominus and Crunket and took them to the surface where they were showed the source of Chi, Mount Cavora. They then blocked up the falls so they could steal all the Chi, but were interrupted by the Tribes of Chima.
Scrug and Scutter were told by Spinlyn that it was the "Great Spider In The Sky" who dropped the Chi into the gorge for them and were confused when Scorm ordered them to use the Golden Chi the mind-controlled Raven Legend Beast to build a statue of "The Great Scorpion In The Sky" and they should be using it to finish building their fortresses, so Scorm hit them with his tail and made them use it. Laval, Razar and Lavertus were then found in the Scorpion Cave and they battled, only for Razar to break the control with gold paint on them and they were beat, then they escaped, but left Razar's Speedor behind which they used to make their own.
Scrug and Scutter tried to get the Lion Legend Beast's armor off so they could control it, but failed. Scorm then brought them away to see their new Speedorz, which Scrug though was pretty.
He later tried to beat Laval with Scolder, but Laval limboed their tail trap and they crashed.
Scrug later helped his brother and Scutter fill in the hole they had thrown the Chi into, when he saw a frozen rock. He licked it and his tongue became frozen. Scolder and Scutter tried to help him but they all got frozen by the Ice Tribe.
He was later held in Sir Fangar's ice trophy collection.
After the Great Illumination, Scrug and the Crawlers were turned nice and became friends with the cured Hunters and Chima tribes, celebrating Christmas with them.