Martine Bancroft: Michael, what's happening?
Dr. Michael Morbius: I went from dying... to feeling more alive than ever. Increased strength and speed... the ability to use echolocation... and an overpowering urge to consume blood.
Dr. Michael Morbius: How far are we allowed to fix something that's broken?
Mentor: Until the remedy is worse than the disease.
Martine Bancroft: I don't want to see you get hurt more than you already have.
Dr. Michael Morbius: This would be a cure.
Martine Bancroft: At what cost?
Martine Bancroft: You're up to something. What is it?
Dr. Michael Morbius: It's not exactly legal.
Answer: He still had a compassionate side, the donated blood was for people who had blood diseases. The reason he did all this in the first place. As for animal blood, that's only for undead vampires, he was a living vampire, who needed specific fresh blood to combat his disease. Plus, vampires drinking animal blood was made up in movies and TV shows.