Abraham Whistler was a vampire hunter who took on a young Blade and trained him in martial arts and as a vampire hunter. Blade, who was half-vampire himself, was given a serum developed by Whistler which would stop him from craving human plasma.

When Blade hunted Michael Morbius, a young human student who was accidentally mutated into a vampire-like creature, Blade discovered the Neogenic Recombinator, which could transform humans into vampires. Whistler told him not to destroy it as it could also be used to cure Blade of the vampire in him. Morbius was eventually driven into hibernation. 

While Blade was hunting a vampire in Europe, Whistler was visited by the Black Cat, who was looking for help to cure Morbius. Whistler told her that the only way he knew to cure him would be to destroy him, and gave her a weapon to do so, but she couldn't bring herself to do it.