This is a rough draft of one villager. When creating a system-neutral project, it can be hard to differentiate between "easily adaptable" and "too vague". For example, I have tried not to be too specific and have left his appearance and a few other things for the GM to decide. I'm not sure if I should add those details - and other more specific information - or leave it open. Feedback is greatly appreciated.
The proprietor of the general store is a former thief who betrayed his partners or guild. He traveled as far as he could, evading his pursuers, and eventually settled in the village. He used some of his loot to buy land and construct a small general store, and buried the rest in the nearby wilderness. He has taken great care to change his appearance as much as possible, and he has managed to hide from his enemies for several years.
His days of thieving are well behind him. He has taken a wife, fathered a son, and is a respected member of the community. He is regarded as a hard working and friendly man, personable and cheerful. He is not violent by nature, but he has killed men in the past and would do so again to protect his family and his new life.
If the PCs befriend him, he might let it slip that he has a talent for picking locks, This information might also be obtained through rumors at whatever tavern or inn the locals frequent. In any case, he will pick locks for a reasonable fee. He will also buy stolen goods, appraise items, and attempt to find any sort of rare or illicit items that the PCs desire.
No matter how how friendly he becomes with the PCs, he will never talk about his true past. If asked he will say that he is from a far away town where he worked as a merchant with his father. He will not accompany the PCs on any sort of adventure, scouting mission, or heist.