In the Monster High Buchreihe, Jackson is the grandson of Dr. Jekyll and Mr. Hyde, making him a third generation monster. The chemicals used by Dr. Jekyll were apparently very toxic and clung to the DNA, passing the condition down to his progeny. The condition afflicted Jackson's father and drove him mad and was possibly sent to a insane asylum (Jackson first thought that his dad just left he and his mother), despite his mother's attempts to help. The only ray of hope Mrs. Jekyll could see for her son was that the change had stabilized through the generations, becoming less violent and unpredictable than its previous forms. As a biochemist she surmised that the chemical had mutated into a more stable state.
Jackson's condition manifested around the age of 13 or 14. Due to the prejudice faced by monsters from humans, his mother protected him by keeping the truth about the family hidden. In the first book, Jackson's physical change is more mental than physical (although in the second book Hyde gains a physical appearance of his own, having blonde hair and blue eyes) and is governed by temperature. When Jackson gets too hot, DJ Hyde emerges, and disappears when he gets too cold.
In the book he wears glasses, likes to paint, and sometimes has pastel stains on his fingers. His mother is the science teacher at Merston High. He falls in love with his next door neighbor, Melody. Jackson eventually learns the truth behind his blackouts when Melody records his transformation on her iPhone.
Jackson and Melody officially go out in Fledermäuse im Bauch. He has a M on his shoe for Melody and Melody has a J on her shoe for Jackson.
He used to be quite shy, but when he found out about being a RAD he got more confident, often defending Melody from the doubtful RADs, and even dissing Cleo at one point.
In the Happy Birthday unterm Vollmond his mother is fired from Merston High for harboring him. He and his mother move out of Salem and is forced to be DJ to protect himself. He doesn't appear until the last chapter of the third book where he's back in Salem.
In Ein Date zur Geisterstunde, he suggested Melody to join Leadfeather, while at the same time sign up for a preformance arts camp over the summer. This lead to a love triangle between Melody, him, and Gargoyle Granite. In the end they made up, and on his own volition became a roadie as DJ.