With Cainhurst Summons in your inventory, head to Hemwick Crossing and approach the obelisk at the crossroads.
Castle Grounds
Entrance Hall
Castle Ramparts
Library
Rooftops
Queen's Chamber
Place the Crow of Illusions on your head and approach the end of the rooftop where you fought Martyr Logarius.
Queen's Chamber
Kneel and swear the Vileblood oath.
Respect
Deep Respect
Blood Dregs are acquired by killing other players or NPC hunters with Corruption rune equipped.
Give her a Blood Dreg.
Give to Alfred
In the Cathedral Ward, at the top of the stairs leading to Forbidden Woods.
Church Bow (Male)
Return to Queen's Chamber