Do you have any ideas how my character could have good morales and still be viable?
You should read http://en.wikipedia.org/wiki/Interview_with_the_Vampire by Anne Rice. If you've got the time /desire to read, that is. The main characters are Lestat (a very evil vampire who relished in torturing his subjects) and Louis. Lestat is the one who infected Louis, and throughout the book Louis happens to struggle with his conscience a lot. He is more of a "good" vampire, in the sense that he doesn't enjoy making people suffer, and attempts to choose victims which are lame, or sick, or not enjoying life. Vagabonds and losers are who Louis tends to drink from. Lestat (on the other hand) would bring a person to near-death as he drank ... revive this person somehow, bring him or her to near-death again. Etc.