Born in Brooklyn to Sarah and Joseph Stevens, Colin was never close to his father who for the first few years of his life was fighting in the Vietnam War. Joseph came back a changed man, he wasn't abusive with his family, just distant and not as loving as Sarah could recall him being, and prone to bouts of melancholy and never seemed able to bond with his only child. Colin loved his father but from that early age didn't have the best opinion of what had happened to him or trust in the US military to do right by its soldiers.
With his mother working and his father distant, Colin spent a great deal of time with his maternal grandparents. Born during the Great War and having both done their part during World War Two, his grandparents were a font of interesting stories - very important things to a boy that spent an inordinate amount of his childhood sick (fortunately for Colin, puberty meant outgrowing many of his childhood afflictions).
It was actually through his grandmother Ethel that Colin found his purpose in life. She had always told Colin she was a historian and had instilled in him a sense of learning from the past in order to make the future better. When Colin turned 15 his grandmother told him what she really did for a living - she was a Watcher and she had been tracking and researching the lives of Immortals for most of her life. Pretty heady and exciting stuff for a fifteen year old but it captured his attention like nothing else and he decided on that day to take after his grandmother and become a Watcher.
For undergraduate he went to Brown and then did his graduate work at Oxford. From there it was off to the Watcher Academy in Switzerland and finally a coveted position with the organization. He was given an active assignment straight out of the Academy - Alwyn of the Cornovii who was currently under the name of Alvin Jones. Things were going smoothly, Colin settled in nicely in Cardiff where Alvin was currently living, and Colin began work on his doctorate while also working in a pub to supplement his Watchers income. Then, three years later Alvin was killed in battle with another immortal.
The Watchers switched Colin over to research where he took over the Ceirdwyn of the Iceni Chronicle. He continued to work on his doctorate and was able to move back to the states, switching to Yale, where he also took courses to get his teaching certification as a backup option for alternate jobs in case he was ever given another assignment.
As luck would have it, when he turned 30, he was given another active Immortal assignment - Ezekiel Gideon. His grandmother, now in her 80s and finally considering retirement, was more than a little excited for her grandson because she had been Ezekiel's Watcher during the 50's and 60's - he was her last active assignment. That excitement of carrying on her legacy eased some of the sting of having to move to South Phoenix rather than being able to stay on the East Coast.
He'd just finished the school year and was looking forward to a visit from his grandmother, and worrying about defending his doctoral thesis in the fall, when the flu broke out. His grandmother arrived in time to have one good day with Colin before she fell ill. He did everything he could for her but eventually had to take her to the hospital - where he happened to run into his assignment. They'd run into one another a few times on a professional basis but he'd never made actual friends with the man despite wanting to try. His grandmother was out of it but not too out of it that she didn't recognize her former assignment and there was a moment when she was left alone with him when Colin asked Ezekiel to watch her when the doctor asked him to step outside. Ezekiel said nothing when Colin returned so he didn't think anything of his grandmother's babbling.
Eventually, sadly, she passed. Colin doesn't know quite what happened to her body as by that point lots of people were sick and dying and he was rather forcefully told to leave the hospital and that someone would get ahold of him for arrangements. No one ever did. He went home and spent the last few days of the human race as he knew it contemplating drinking to the point of oblivion but never quite getting there. Eventually everything settled down he knew he had to do something - especially since he'd begun to have the strangest dreams...
Colin was never one to be alone for long so he set out to find the one other person he knew for sure would be alive in Phoenix - Ezekiel.