I am also replying to old posts. Hoping to stir up new ones.
The circumstances surrounding the Blys in Rhode Island have their roots in King Phillips War, in my opinion.
You need to look up the war for the details, but here's a bit I've written for another post:
A brutal war was taking place in New England from about 1675 to 1679 Nearly half the towns in New England were attacked. Many settlements were stroyed and the people killed, some in extreme brutality, skinned alive or gutted, left to crawl around blind until they died. The war nearly brought the New England economy to a halt, driving the colonists back to the protected strongholds on the coast. They formed an army to fight the Indians with men from all over the colonies joined together for the first time. Over 800 colonists and possibly 8000 Indians were killed. Brutality on both sides was unbelievable. The conclusion of the war, sort of, took place in the Great Swamp, Narragansett land - what is now the area around North Kingstown, Rhode island. The settlers finally cornered King Phillip, killing and burning as many as 600 Indian families in the stronghold of the swamp. King Phillip's head is said to have been stuck on a pole at the entrance to Fort Plymouth where it remained until it crumbled.
Daniel Bly appears to have one of the men in the colonial militia as his name appears in the Salem area first, then in Kings Towne in 1679, the last year of King Phillips war, in the place where it ended - the Great Swamp. He had a child there, and later in 1709 he bought land there, known as Bly's Purchase, or Swamptown.
The vital records of North Kingstown burned in the 1800s so there is no way to tell exactly what the family lineage is, but I believe Daniel and his contemporaries were the first ones there, out of Boston.
A massacre occured in Cumberland, though I don't know many of the details.
The first massacre occured in Springfield and was horrific. Most of the families were killed. This may be the source of Oliver's madness.
Another Bly went to Springfield from the coast - Samuel - early in the 1650's from what I have been able to find so far. This was an outlying settlement that opened up due to a new treaty in 1650. I believe Samuel is the son or grandson of Thomas Blyth of Boston. Thomas, John, and Margaret were in Boston at the same time in the early 1630s. They may have been her sons. Daniel is of the same generation, but younger.
Oliver and others may be located by old military records if they were alive at the end of King Phillip's war. As more and more records become available online, I believe we may be able to make the connections back to the Boston Bly family as the first generation here for the New England Blys in Massachusetts and Rhode Island.
I know this doesn't give you the person, but maybe it will give you new avenues to look into.