Malachi is what one would describe as a "good guy." He doesn't get into trouble, he follows the rules, and he respects his peers. Well, most of them anyway, unless they've done something to piss him off, which is rather hard to do. Mal is known to be notoriously relaxed--he's the definition of cool, calm, and collected. He's a very logical person, and when everything is planned correctly, and everything is being executed correctly, then he sees no reason to panic or fuss over a situation. If it's under his control, he's happy with it.
Malachi can be too logical at some points; while he's generally a very pleasant person, he can be blunt and has a trademark sense of honesty. If he isn't telling the truth, he feels as though he's committing a disservice or a sin against his friends and family. Due to his calculative personality, unless he has a closely maintained friendship with a person, he can seem distant and cold to outsiders. This is in part due to the "collectivistic" nature of many Latin American cultures, and the circle of relationships Malachi maintains (which is rigid in permeability). In other words, it takes a long time for him to really trust someone, but once he does, they're family to him. On the other side of the coin, even if the person is toxic and causing him pain, Malachi finds it hard to let go of that relationship or friendship (unless they are causing pain to other important people in his life). Mal has very distinct morals, and he sticks to them, no ifs, ands, or buts.
He's quite intelligent, and is a very strategic person. In fact, his dream job is becoming a professional dueler, a profession in which one is required to come up with strategies and attacks and counterattacks on the spot.
For all his apparent distance, though, Malachi has a soft spot for his family, and especially his little sister, Bianca, and for his mother, Valeria. He's very happy with the recent addition of his step-father, as Kevin could be a lot worse, and the two seem to have a healthy, good relationship. (Secretly, Malachi really likes Kevin, and he's happy his mom is happy. When they first started dating, Mal asked his mother if Kevin could adopt him, but he'd been 9 at the time, so he blames his age on his lapse of judgment).
Malachi is quite tall for his age--at 5'9, he's easily one of the tallest boys in his third-year class already, and his stature paints him as rather intimidating. He's got incredibly fluffy, untamable chocolate brown hair that tends to not get cut often, and hangs in dark brown eyes. His skin is very deeply tanned, and he's currently in the "lanky" phase of his growth spurt, but he knows he'll eventually fill out.
Born on November 21st to Valeria Çenturion, a single mother, in the US, Malachi grew up with a younger sister and his mother after they moved back to Argentina, where Valeria's family lived. Malachi spent the first two-and-a-half years of wizarding school at one of the magical schools in Latin America before his mother remarried and decided to return to school in America, where she is studying to be a nurse.