Well we know now that Lucifer bore the mark, they try to imply in S10 that he went unstable because of it's influence. If it turns a human into a demon with little effort, I have no idea what choas it could work on an angels brain.
Angels seem to be very programmable, made to obey, the Darkness working such a malliable one would certainly leave residual behavioural issues.
Michael may have been able to get through to him? who knows, maybe faced with the Darkness as an adversary, he'll change his mind.
And I'm not sure archangel is an upgrade, the 9 orders are meant to be absolute, not interchangable, but they already tossed that idea out, I don't know.
Angels seem to be very programmable, made to obey, the Darkness working such a malliable one would certainly leave residual behavioural issues.
Michael may have been able to get through to him? who knows, maybe faced with the Darkness as an adversary, he'll change his mind.
And I'm not sure archangel is an upgrade, the 9 orders are meant to be absolute, not interchangable, but they already tossed that idea out, I don't know.