Vampires do change, and it probably involves inner psychological identity, so probably one of the vampire stories here.
- "If any one plot is truly magical, metamorphosis is it. Most of the master plots are grounded in reality: They deal with situations and people whom we readily recognize because they're based in our experience. Even good science fiction and fantasy stories are ultimately as real in their portrayal of people and events as anything by Henry James or Jane Austen. Science Fiction author Theodore Sturgeon pointed out that a good science fiction story deals with a _human_ problem and a _human_ solution. Fiction, whether it happens in Middle Earth or in a galaxy far, far away, is always about _us._ Fiction reveals truths that reality obscures." "...In the metamorphosis plot, the physical characteristics of the protagonist actually change from one form to another. ..." animal to human, human to beast, etc. with change that is physical and emotional. metaphor, allegory, and mixes...wolfman, vampire, beauty and the beast, etc. http://www.mit.edu/~mbarker/exercises/exer970801.txt
- In this fantastic plot, the protagonist is physically transformed, perhaps into beast or perhaps into some spiritual or alien form. The story may then continue with the changed person struggling to be released or to use their new form for some particular purpose. Eventually, the hero is released, perhaps through some great act of love. http://changingminds.org/disciplines/storytelling/plots/tobias_plots.htm
- this plot involves the physical characteristics of the Protagonist actually changing from one form to another (reflecting their inner psychological identity). http://www.tennscreen.com/plots.htm