Malcolm's story is not very known, he was a member of the Gemini Coven who was banished from the coven because he was a Siphoner. Malcolm was supposedly born in 1828. Later he met Lillian Salvatore, in late 1858, a vampire who later turned him into a Hybrid; half-vampire, half-witch. He was trapped in the 1903 prison world with Lily and his fellow Heretics.
Malcolm himself was turned into the second Heretic in the year 1864, after Valerie became a Heretic. Malcolm was intrigued with the idea of having magic constantly at his disposal instead of having to siphon it from other sources. He managed to successfully convince Lily to turn him, Lily feeding him her blood and snapping his neck.
Malcolm and the Heretics travelled from England, back to America on a ship. Lily found someone, whom was dying of consumption. Lily took pity on him and turned him into a vampire intending him to be a new member of the family. Just before docking, Lily and the Heretics drained and killed everyone on the ship. On the docks, they were confronted by the Gemini Coven and were sent to the prison world, where they were cursed to relive that same day, over and over again.
After spending many years in the prison worlds, they eventually began to run low on blood. They had already drained every butcher on foot. The Heretics made a sacrifice and let themselves desiccate so that Lily could live on.
Malcolm is arrogant and sarcastic, but is shown to care for the well being of his "family", as he brought many of them to Lily and saved them from their families. He views his fellow Heretics as his siblings, and Lily as his mother and the love of his immortal life, however Lily does not reciprocate these feelings.
As a ripper, Malcolm often has difficulty controlling his bloodlust. Unlike rippers Stefan and Lily, Malcolm genuinely enjoys hurting others and feels no guilt or remorse for his actions after he has come down from a blood high. Malcolm, however, has been able to gain complete control over his bloodlust in the past for the sake of his family and Lily and even for a time, kept his bloodlust under control after getting back from the 1903 Prison World for Lily's sake.
Malcolm has also been described as crude by Nora and Mary Louise, and is said to be the most vile and wicked of all the Heretics when Lily isn't keeping him on a short leash. This being said, Malcolm has outright ignored or went against Lily's wishes at times, one of these times being when he joined his fellow Heretics in getting vengeance against the Mystic Falls Gang. Going by this, one can assume that Malcolm has a real vindictive side to him and his need to avenge himself or those closest to him outweighs any loyalty he has towards Lily.