MacDonald 'Maximo' Dalton is the protagonist of Los Santos Chronicles - Killer Instincts.
MacDonald is a mute contract- and serial killer working mainly for a hitmen business run by Mr. Green.
What is known of Mac's background is revealed via two hallucination sequences in missions Nightmares and Nothing to Be Afraid Of.
Mac was born somewhere on the East Coast to unnamed parents. His father was a gardener and mother a home cleaner. Mac's first encounter with death was when he found a badly disfigured body in a forest near their house at the age of 6. It gave him nightmares, but at the same time fascinated him in a strange way.
On Mac's 8th birthday, their home was attacked by an infamous mass murderer old man known as the Swine Slaughterer. The psychopath in a pig mask murdered Mac's parents later he opened his mask and Mac saw Slaughter's face, Slaughter has got short white hair and white mustache that means he is old man, while he watched in horror from a closet. The event left him traumatized, resulting him forgetting the faces of his parents but he didn't forget Slaughter's face and remembering them as a bloody mess they were.
For then on, Mac was forced to live with his abusive godfather and uncle, Tony. Uncle Tony was a roofer, and made Mac assist him. He was also an alcoholic and abused Mac. He even cut of Mac's tongue and made him eat it.
Mac withstood the abuse for 10 years. At the age of 18, Mac had enough and killed Uncle Tony by pushing him down from a roof. Mac made it seem like an accident, and the police didn't even suspect him. The fascination of the dead body he found as a child kick in again, and Mac learned he liked killing. He became a notorious hitman and contract killer, working for several employers.
Over the years, as Mac's reputation as a killer grew, stories started to spread, telling how Mac cold-bloodedly murdered his parents and uncle as a child, lived years in the woods killing and eating hikers and so on. No one is sure about Mac's past except he himself and he met Mr. Green.
Prior the events of Los Santos Chronicles, MacDonald was arrested for the murder of a senator he did in orders of Mr. Green, and sentenced to Bollinbroke Penitentiary. After being incarcerated for two months, Mac is released due to lack of evidence.
Mac returns to do hitman jobs for Mr. Green in Los Santos, until he meets a mysterious man who twice gives him a letter saying; "Lombak Tower, room 66".
Mac goes to the Lombak Tower room number 66. There, he meets Lincoln Jones, the leader of an international terrorism group NightHawk. Jones needs a skillful killer like Mac, and in exchange offers to find the Swine Slaughterer for Mac, the psychopath who murdered his parents. Mac accepts the offer, and his first mission is to kill Mr. Green to prove his loyalty to Lincoln and to get revenge as Lincoln reveals Green to be the one ratting Mac out, leading to his arrest.
Mac starts working for NightHawk by helping the organization's drug manufacturer, Dr. Zokuux, create a new powerful drug and stealing delicate files about Peter Pines. Pines, a multimillionaire, also promises to support Mac finding the Swine Slaughterer.
Mac meets a TV journalist Mary Cummings, who's been on the case of the Slaughterer for some time. He has a reliable contact providing her with possible info about the serial killer. Mac works with Mary, but her contact is revealed to be the Swine Slaughterer himself, who's been leading Mary astray all the time. During their meeting, Mary is injured, and Mac takes her to a hospital. Slaughterer gets away.
Zokuux's drug, which he dubs Oblivion, is completed, but due to its addictiveness and the maddening hallucinations, Pines can't allow it to get distributed. He orders Mac to kill Zokuux and destroy every trace of Oblivion. After a co-op mission with Lloyd Tederev, Mac finds Pines' dead body in his penthouse, Swine Slaughterer's calling card by his side.
Lincoln contacts Mac, telling him he needs help. As soon as Mac arrives in Lincoln's office, a squad of heavily armed hitmen attacks them. Mac helps Lincoln escape, who decides to go into hiding, meaning he can't help Mac anymore.
Not long after, the Swine Slaughterer himself contacts Mac, arranging a meeting with him at the Mile High Club.
There, Mac chases the Slaughterer up the building, playing a deadly game of hide n' seek with him, while the Slaughterer tells him how he feels they are much alike. Like blood brothers. It being the reason he has let Mac live all these years. They eventually reach the top of the building, starting their final duel.
Mac shoots and beats up the Slaughterer and keeps torturing him. Lethally wounded, Slaughterer tells Mac, that by killing him, he also kills his only reason to live. Mac won't listen and cuts the Slaughterer's head off.
Some time after the final showdown, Mary calls Mac, thanking him for saving his and telling the Swine Slaughterer's mutilated corpse has been found. Mary hopes Mac would come visit her in the hospital, but Mac hangs up the phone.
Ms. Green - Killed for sending Mac to prison and to prove loyalty for the NightHawk.
Swine Slaughterer - Murdered to avenge the death of Mac's parents.