Doctor: Well, I'm just trying to process this information. I don't get many vampires coming in here...
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*a while later*
*Rex comes in*
Rex: Um...we have bad news and...sort of ok news. The Bad news is that we were unable to find records of a birth certificate for you, meaning Sarge is not your real name, which I'll get into later. The sort of ok news is that we did find some incomplete records of a lab specializing in memory alterations that was separate from the scientists. But it seems as though the scientists deleted most of those records and took control of the facility.
What we could patch together from the information we did have was that...um...Sarge is just a nickname they used to keep your real identity a secret for your protection...Your memories were scheduled to be altered, though it doesn't have any details about just what was being altered and what to. it also seems as if a very advance gender changing procedure was scheduled. Due to your already natural ability to shapeshift, I would bet that your body just accepted whatever gender it was as just another form...