Nick Valentine (human)

 was a brilliant Chicago police detective, who transferred to Boston in order to aid in taking down Eddie Winter as part of Operation Winter's End. Coming in highly recommended by Commissioner Turner, Valentine brought his fiancee, Jennifer Lands, to the city. Valentine's mission was to track down the various holotapes sent out to mob associates where Winter incriminated himself, so that the police could mount a case against him. Those holotapes were the key. In the course of the investigation, the investigators confirmed that Eddie Winter was involved in every crime imaginable, from petty larceny to first-degree murder. The push by the police was not without pull: Winter's goons tried to intimidate the task force and gunned Lands down. Though mourning her loss, Valentine persevered and tried to bring the case to an end.

It wasn't Winter's end.The BADTFL was working together with Boston's District Attorney to take down not Winter, but every other criminal family in the Boston metropolitan area, and Winter was the means to achieve this ambitious goal. In return for his cooperation, Winter was granted immunity from prosecution and simply walked out of the office. The task force was disbanded immediately after obtaining the evidence, leaving the police men out in the cold. Nick Valentine was left a shell of a man. Captain Widmark did arrange for Detective Valentine to take part in an experimental CIT brain scanning program to help him cope with the trauma... And granting him immortality when the brain scan was used in an Institute experiment over a century alter to create a special kind of synth.

Ironically, this would allow for justice to be served more than two centuries after Valentine and Winter faced off in the streets of Boston. While the original Valentine died, the synth lived on with his memories. And Winter, now ghoulified, had it a Long Time Coming.

Appearances
is mentioned only in Fallout 4.