There are mods which curb random NPC biting, and prevent file corruption which can be caused by changing the creature states of characters(such as Mrs. Crumplebottom is on the lot, she is at risk of being bitten, and that can corrupt core files in the game. Note that once a Grand Vampire has bitten a playable Sim, any Sim, playable or not, who comes in contact with a Grand Vampire is at risk of being bitten, regardless of their relationship with the Grand Vampire. Once the Sim and the Grand Vampire have a high enough relationship, get the two together, and the Grand Vampire may bite the Sim.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.

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