Sanctify them in the truth
There was a ritual element to the murders. There had to be. There were practicalities, like never killing someone that could be tied to his personal life, to keep the police at bay. And then there were Rules, the commandments that came from his soul and could not be bent or broken.
It was two in the morning. Nicolas was in the secret second home of his latest victim. This one had been hard to catch, since he was a priest. Nicolas could not enter a church while he was hunting. He could not kill anyone wearing a rosary or a cross. There were Rules. But here? Where the fire-and-brimstone preacher came to have his affairs? Here, his hypocrisy would be exposed to the world.
The middle-aged man was bound and gagged on his own bed. Nicolas had drugged him, to restrain him. But he was awake and aware enough to look afraid as Nicolas approached with the needle. They had to be alive when he drained them, he had to stop before the heart stopped. That was a Rule. The first syringe of blood was squirted directly down his throat. He had to taste it, that was a Rule, too. But he had about two liters to drain, and he couldn't drink all of it. The rest was delicately poured into an empty champagne bottle and two glasses, set up in a mockery of a romantic date at the dining room table. Bright red rose petals led from the table to the bed, where he left the man dying, two puncture wounds in his neck.
Back at home, he changed out of his clothes, an eighteenth century getup that would have fit a period piece about the revolution. The gloves were practical, yes. But he needed to maintain a connection to his true self when he was hunting. He slept through most of the day. Come evening, he got up, dressed in a band t-shirt and ratty dark jeans, and went out as Nicolas, local musician.
Arriving at the club, he saw Mina already sitting at the bar. He sidled up on the stool next to her. "Hello hello." Mina had an unhappy expression on her face. "What's stuck in your craw tonight? The music's not that bad," he joked. Befriending Mina was the riskiest thing he did, but he couldn't resist. She, like him, was an agent of truth, in a way. He could feel the spark in her.