Marion Boyd was born in Chowan County sometime in the early 1750s. The daughter of a local planter and justice of the peace, Marion married Dr. George Wells in 1767 after her father granted special permission, as Marion was still a minor at the time. The Wells' marriage was evidently a strained one, it seems that George Wells might have had little contact with his wife, and may have been somewhere outside the colony for much of the time. Marion's father's will in 1775 expressly left a portion of his estate to Marion but not to her husband, noting George's prolonged absence, and that Marion and George had "no connection."

In 1774 Marion Wells and her sister Lydia Bennett were two of the fifty-one women that signed a nonimportation agreement which later became known as the Edenton Tea Party Resolves. Marion's husband George Wells died by 1784 and that spring Marion married John Mare, a former painter from New York who worked as a merchant and postmaster in Edenton. The Mares had two children together and she died in Chowan sometime prior to John Mare's death in 1803.