Malcolm was the son of Court Jester Heinwald and Princess Thelia. As a kid he liked to torment animals.
He became the court jester and close friend of King William the Generous. He is also reported to have been friends with Williams wife, Queen Katherine, the intro describes him as having been a favourite of the Royal Court at one time.
But one day, perhaps drunk with power and greedy for more, Malcolm assassinated the royal couple and seized control of the Kyragem. In response Kallak, leader of the Order of Royal Mystics created a magical seal that trapped Malcolm inside the Castle. However this also made the Kyragem inaccessible to everyone except Malcolm, and without magical reserves, the mystics power diminished. For 18 years Malcolm plotted his revenge until the day the spell holding him prisoner finally slipped, and he was able to escape.
Malcolm immediately started wreaking havoc on Kyrandia, destroying trees and blowing up squirrels on a whim, as well as hunting down each of the Royal Mystics. Kallak, the first to fall victim, was alerted and wrote a note, warning Brynn and asking her for help before Malcolm finally caught up to him and turned him to stone. Not long after Brynn explained the situation to Brandon and helped him gain the amulet, Malcolm abducted her.
Brandon first met Malcolm in person outside Serpent's Grotto while the latter juggled with knives, mocked and tried to dissuade Brandon from continuing his quest. Before leaving, Malcolm sealed the entrance to the maze with a block of ice. Darm disappeared soon after and later turns out to have been Malcolm's next victim.
Later, Malcolm is seen again near the Enchanted Fountain, wrecking it so that it stops pouring out magic water. He then abducts the last remaining Mystic, Zanthia.
Malcolm mockingly "welcomes" Brandon as he enters the Castle. Surprisingly he is willing to tolerate Brandons presence, but forbids him to enter the Kyra-vault. All the mystics he abducted can be found in various rooms of the castle turned to stone, and its shown that Malcolm also abducted Herman casting a spell on him making his skin turn green, his eyes turn red, and causing the normally friendly bridge keeper to become dangerous and homicidal. Fortunately the healing gem causes Herman to fall into a deep sleep, rendering him no longer a threat, but cannot undo the spell.
Malcolm himself only confronts Brandon after he unlocks the entrance to the vault.. After taunting and shoving Brandon several times, he causes Brandon to lose his temper and is punched unconscious. He wakes up again soon after Brandon enters the Kyra-Vault and shoots a spell at Brandon to turn him to stone as well. but Brandon tricks him by turning invisible and standing in front of a mirror, causing Malcolm to miss and the spell to rebound back off the mirror and hit Malcolm instead. With Malcolm turned to stone all his spells are nullified and his victims restored.
Malcolm is mostly not present in the second game but one of the letters you have to collect has an easter egg referring to him, and a scene after the credits implies his return.
In Malcolm's revenge Malcolm is freed from his statue (which has been moved to the rubbish dump) by a freak bolt of lightning. Although as snarky and with the same mean sense of humour from the first game, its shown that Malcolm may not be quite as evil as the first game led us to believe, and that he did NOT kill William or Katherine, in fact even on his rampage in the first game, he seems to have drawn the line at outright murder (of people at least) according to a conversation between him and Kallak. Kallak states that Malcolms "lack of cooperation" will be noted in his file, to which Malcolm snaps, "my file will include a legitimate homicide if you don't SHUT UP!" indicating it would be the first, and a flash back at the end of one of the three routes shows Malcolm visibly upset over William's death. Whether Malcolm seeks redemption or revenge (or neither) is up to the player.
In this game on the redemption route, Malcolm can befriend and be welcomed back by Darm, Brandywine, and Zanthia, despite everything he did in the first game, but Kallak remains hostile to him, and Brynn's reaction is unknown as she is nowhere to be seen.