Zero
It would be so easy to parody Drusilla. She's demented. She speaks in nonsensical phrases and believes her delusions. She plays with dolls, loves with Spike, and hates the Slayer. Badda-boom, badda-bing, you've got Dru.
It would be so easy to miss the shadings of personality and intellect that are a part of Drusilla. Throw in a few references to that blasted Miss Edith, babble about naming the stars, and forget that this child-like vampire is a demon that has survived for a long time. Longevity in vampires is a thing of pride, and rare.
Zero knows Dru like the back of her hand. Her ability to bring forth the madness savant in this tortured woman is unparalleled. And her Spike is nothing to sneer at either.