Quin didn't walk away pure.
He walked away aware.

You don’t exorcise knowledge.

You endure it.

He didn’t just witness something supernatural... he participated in something eternal.

That puts him on a collision course with the Vatican, the fallen, the living, the dead, and whatever is left in his own conscience.

He will forever have that moment behind his eyes:
 

The throne,
The marble,
The black wings,
The contract that almost bore his name.

Tilly saved him.

But Sarielah left her mark.

And Severin? He knows exactly what Quin is now:

A liability with inside information.