Basically, press the green flag and enjoy my artwork! :]
Derp Core is the first Core with a Visor instead of one eye. Years ago, he was the Smart Core. The Smart Core helped with inventions, and even helped with the Portal Gun itself! But one day he was working on an experiment involving explosive barrels, when all of a sudden the barrel exploded and broke Smart Core's management rail. He fell to the ground and he was damaged very badly, and was thrown into the corrupted core chamber. But when the Portal Wars started, GLaDOS needed all the help she could get, so she released him from the chamber. But in all those years he was kept there, he turned into the Derp Core. He can now turn from Derp Core to Smart Core, but he can't control when.