Then may I recommend Kin Newman's "Anno Dracula" series? In that series, Newman posits that some of the Vampiric Weaknesses-Water, the Sun, not showing up in mirror, etc-are actually derived from Bloodline; in pretty much the same way we inherit certain traits from our parents...

Dracula's Bloodline is generally regarded at tainted compared to other Vampiric Bloodlines.

There are Vampires that can go out in the day, especially if it's cloudy out. Further, there's nothing like shoving a cross in an atheistic Vampire's face and realizing the cross ain't doing what you expected it to do...