It may not be possible to build the relationship high enough for the bite neck interaction to become available, but at least get it high enough for the Grand Vampire to accept a phone call or invitation. Have the Sim(s) talk to the Grand Vampire, and build a relationship with him or her.If one of them is going to appear, it may take a while, so make sure the Sims have high motives, or that they keep them up. Send one or more Sims to a Downtown community lot at night, and wait for one of the Grand Vampires to appear.
