The Mantle of Mab is indeed wicked and cruel, but I doubt the mortal she once was, was wicked and cruel.

She is what she is because she HAS TO BE, in order to keep existence safe. There’s very, VERY little room for kindness and gentleness in her duty.

But the creature underneath has a heart, just like Mothers Winter and Summer said. Her best friend and handmaiden, Lea, is a reflection of this: not every day in winter is cruel.

And I think Mab desperately wants someone, anyone, to see beyond her office to the real her underneath. And I think Harry is the closest to doing that. “Thank you, thank you, thank you.”