From the Dancers set:
The mirage-like aurora veil is said to be an article of the old gods, permitted only for direct descendants of the old royal family.
The black eyes of the Pontiff eventually transformed the Dancer into a beastly creature, her gauntlets fusing with her own hide.
From the Dancers soul:
The Pontiff Sulyvahn bestowed a double-slashing sword upon a distant daughter of the formal royal family, ordering her to serve first as a dancer, and then as an outrider knight, the equivalent to exile.
From Irithyll straight sword:
Every Outrider Knight one day devolves into a beast, constantly hounded by Pontiff Sulyvahn's black eyes.
From Pontiff's left eye, obtain from the soul of vordt
Bewitched ring that Pontiff Sulyvahn bestowed upon his knights.
Knights who peer into the black orb are lured into battles of death, transformed into frenzied beasts. No wonder the Pontiff only provides these rings to those dispatched to foreign lands.
From Soul of pontiff:
Pontiff Sulyvahn of Irithyll imprisoned a god of the old royalty (Gwendolin) in the abandoned cathedral, to be fed to the devourer (Aldrich)
And we know that Sulyvahn trapped Yorshka in the tower from her dialogue, wrongfully proclaiming himself Pontiff when the entire royal family was out of the way.
The Pontiff killed, corrupted, or imprisoned every remaining member of Gywn's family, using both aldrich and the royal family to do his bidding now.
Hell, if you look really deep into it there's even the implication that he's somehow responsible for the current state of the twin princess considering his minions are all over the place at Lothric castle and that the statue in the courtyard with the winged fatty shows the profaned great sword, and considering he's basically using Aldrich to do his bidding there's a chance he has some command over the deacons of the deep.
Dude has his hands on everything.