Erica's Slow Turning

Count Yorga, Vampire (1970) - At the start of the movie, Erica, along with her boyfriend, Paul are attacked by Count Yorga the night they had drove him back to his manor. Paul was knocked out trying to defend Erica, allowing Yorga to bite and feed on her without any resistance. The following day, Erica is revealed to have lost some blood and is a bit more stoic but seems fine... that is until Paul and his friend Michael come to check on her.

Example of:
Vampire Refugee