Not sure what you are asking. The OP is pretty clear, New England ran the international slave trade.
Not sure how you don't know what I'm asking, can it be any more straightforward than:
"What "fault" are we talking about in this context, slavery?"
I mean obviously I'm asking what the fault is. Not sure I could've worded it any more clearly.
Also the OP includes
"Of course, it wasn't the New Englanders' faults, They were only responsible businessmen who had every right to make a profit –and a handsome profit it often was."
You might notice the context of fault isn't included, I didn't see where this was stemmed from, hence instead of assuming it was slavery I figured I'd ask for clarification.
So is the fault being attributed to New Englander the international slave trade specifically or the system of slavery (which was far more involved than just the slave trade?
Again I don't want to assume incorrectly and respond pointlessly, one should welcome requests for clarification rather than challenge them.
New York protected it, until the bitter end.
How did New York "protect" it and clarify "bitter end" please... Events, actions, etc would be valid sources to back up such a claim.
Yes, their customers were hungry for more, but these guys in the North were the 'drug dealers' of the 19th century.
That's not a very good analogy. Drug traffickers is more accurate, the dealers were the slave markets mostly in the South. Unless you are arguing the Northerns controlled the slave markets in the South.
Additionally, in context to the whole New Englanders and the international slave trade, I started a thread about who owned the slave ships
https://civilwartalk.com/threads/who-owned-slave-ships.143347/
Do you have some source that proves "New England ran the international slave trade. "
The first piece of data I found there suggested Britain might be a better candidate with about 66% of slave ships flying the flag of Great Britain.