Some endings are very hard to find, it is also very important to get as far in the dialogue as possible before "attacking". For those who want a walkthrough to get the hardest ending, read further.
vv --- SPOILERS BELOW --- vv
Thank you kindly – You are my guest – You're up past bedtime - You are quite appetizing – I'm a vampire – I can't tell, you won't understand – I don't know anymore – I have lived many lives – I give life eternal! – I live for the hunt for blood – I prey on humans because I have to.