Alien-Vampire hybrids are actually possible..
DISCLAIMER: this is not officially supported, attempt at your own risk, while I'm not certain it COULD corrupt your save game Looks like when we were told there were no hybrids, it wasn't completel...
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Another possibility would be to have an alien/human hybrid offspring (one that looks human, but has alien powers) become a vampire. They would probably retain the vampire and alien powers. They also wouldn't have the disguise and dark form conflicting. If you have CC you can add things like elf ears and green, blue, or some other colored skin tone to make them resemble an alien.
