Deception scenario

[Belmount]

Hey everyone,
I am building a campaign and I want it to be very engaging and make the characters have heavy choices. One of my ideas is to secretly have one of the members be secretly bit or changed. They will get an extra ability but must kill and feed on townsfolk. This PC can choose to reveal himself to the party and try to be cured or keep it a secret and enjoy the extra ability. If they choose to keep it, It will eventually be revealed later in the story and cause some turmoil. Can you guys help me think of an ability or feat that might be useful (not game breaking) that might entice the PC? I am using the 3.5 books. Thank you.

[Almarck]

I am afraid this may not be the place to get advice on planning a campaign. World building is about a setting to play in. This on the other hand is a campaign. While campaigns can take place in original settings the scope of settings is far more than campaigns and it is more of a question of world building than story building.

Instead you want to go here for campaign building help. http://www.giantitp.com/forums/forumdisplay.php?59-D-amp-D-3e-3-5e-d20

People there will respond eagerly.