Dampyr #172 (2014) page 65: Test of loyalty

Olimpia explains the implications of Harlan's status as a Dampyr:

“He can detect the presence of the Masters of the Night and is the only one capable of killing them. His blood is lethal for vampires, and his main occupation seems to be hunting people like me.”

“Does that worry you? Do you think he can find you?”

“He definitely will. The trail of death we have left behind is unmistakable. We must find him before he finds us, and keep our eyes open.”

“Hmm! Okay.”

“When I asked you to prove your love to me earlier, I meant that sooner or later I will ask you for a proof of loyalty.”

“I will do what you want, Olimpia.”

“I am sure you will.”

In other issues of this series, the vampires are often unaware that Dampyrs even exist, but clearly Olimpia is better informed.