Lord Eldred, in that case you definitely do not have to grab their heritage. Thus you do not need to be e bloodhunter. You could just try to kill them, in order to be rid of him, or destroy his tie with his bloodpower (something like suppress blood line, destroy bloodline etc). If you are a bloodhunter and you only search for those who use their heritage to harm others, you won't have the greater chances on blood theft (since you do not grab the blood powers, you just destroy them, with various means). In that case you could enven be LG in alignment.
It's all about motivation and what you hope to gain each time you do something...