Long time kinkish-canon vampire biology, where vampires climax with blood (In all sexes). Bloodier it is, the more they are enjoying themselves (and encouraged societal too, so enthusiastic messes are common)
so have vladd making a real big mess
(doesn’t help that his own blood is very close to human blood, so it looks like someone died rather than a strange sometimes neon dipped spray-paint.) (like idk, drac, who is verry verry blue colored)