FAQ

Likely the ancient vampire language.

Simply put, it's because actress Leonora Varela actually has a scar on her lip and Director Guillermo Del Toro felt she was the best actress for the part and didn't feel that was a good reason to not give her the role.

One could possibly come up with their own in-universe explanation as to how a vampire could receive a permanent scar, but there's no official reason.

Blade II is based on a vampire hunter featured in Marvel Comics. He was created by Marv Wolfman and Gene Colan. Blade's first appearance was in The Tomb of Dracula #10 (July 1973) as a supporting character. The comic book Blade was adapted for the movie by American screenwriter David S. Goyer. The first Blade movie, Blade (1998), was released in 1998, followed by Blade II. A third sequel, Blade: Trinity (2004) followed in 2004.

While it's never explicitly stated, Blade is seen with a large supply of Serum, in much smaller bottles from the first film. The amount of these he has suggests he does not need to increase his dose - Chances are, once she developed this, Karen left - either to return to a normal life or to join another group.

There are a number of theories: (1) A line of dialogue from the film explains, "He shot himself and then he turned", as says Rush, the vampire Blade allows to leave as a "loose end" for showing him Whistler. So it's likely Whistler shot himself under the chin, but the wound wasn't fatal (I.e. did not travel to his brain) so the vampirism healed him (2) Director Guillermo del Toro argued that no one saw Whistler shoot himself (in the DVD commentary), so he really didn't die in Del Toro's eyes; and (3) A deleted scene from the original Blade. When Blade and Karen were climbing out into the daylight after Blade had just blown up Deacon Frost, there was a figure in the background that appeared to be Whistler. It was hinting at him returning in a sequel, but the filmmakers decided to leave it out of the film. (This was actually supposed to be Dr. Michael Morbius, but they didn't have the rights to him, and so cut the scene)