Born in Limerick in 1983, Marcus grew up in a relatively poor family, wasted by gamblers. The Arthurs dated all the way back to the 1300s, where they came over to Ireland as Normans. His family was relatively well known in the Republic of Ireland prior to his birth, but due to some ill doings, they were eventually hated severely by the Irish community, and decided to move to the UK. He moved to Leeds, England in 1990, where he trained as a paramedic.
Marcus remained in England after returning from Ireland until 2000, eventually moving to Chernarus. He had learned extensive medical training in Leeds, and decided to become a paramedic in Chernarus, seeking a new job opportunity.
By the time shit hit the fan, Marcus was dealing with those infected, until they grew too many in number. He decided to leave the medical work, running off, as the numbers of infected grew and grew. He decided to remain within smaller cities, atop rooftops or in hospitals, attempting to scavenge medical supplies. He would often trade supplies with other survivors, or provide medical assistance to those who required it, working for free, only out of good will.
Surviving Chernarus alone is difficult, Marcus decided to push himself towards a hunter's trade, tracking down animals in woodland, or nearby old abandoned towns, downing them and taking their meat, for either food or trade, whichever he could strive off best.