So, The Dhampir

When a vampire reaches its last remnants of energy, it goes into a sort of hibernation, being sustained only by the evil that goes to and fro in the earth, waiting for a splash of blood. When blood is absorbed and prey is near, the vampire rises, wroth with frenzy and desperation, seeking to feed. Of course, this is the normal process. However, should a vampire be interred in hallowed ground, or within a sealed coffin of a pure metal, it will instead continue to starve, unable to feed on vermin or unquiet spirits. The last vestige of darkness haunting the corpse will die. The corpse, however, remains revivified. In fact, it has been discovered - regrettably, in hindsight - that the "obvious" vampire symptom of being flush with life, was actually the beginning of the dhampiric transformation.

As hell's darkness leaves the corpse, the suppressed soul of the mortal refills it. The body is no longer forced to reject mortal sustenance, though it appears that their more esoteric abilities do still necessitate a sanguinary diet from time to time. Additionally, many of the vampire's weaknesses are purged along with the vampiric mind (that entity which perverts and suppresses the mortal soul of a vampire). Sun, silver, and even holy oil have no effect on these beings. Luckily, they seem to occur only when a human's will is strong enough to prevent the vampire from feeding, and they are fortunate enough to be interred as necessary for a sufficient duration. As a result, those few dhampir which do exist are looked upon by our church as allies, although they trust us far less. This, of course, is understandable, given the quantity of them slain at our command before we learned their true nature. 

They are Providence's gift to the penitent vampire, and carry a spark of fortune's light within their soul. The so-called "Vampire Lord" could be considered their own dark mirror. Please bear this in mind while more information regarding that subject is collected.

~Emmanuel Blochleach (in a letter to the Royal Athenaeum)