Mark froze as he heard a sudden wrap on the door. Then, mentally chiding himself, he remembered that Gene, the graduate student that lived next door, was going to come over tonight - he'd asked Mary to help him edit his masters thesis. There was another knock on the door, and Mark quickly glanced around, trying to find something to cover up his nakedness. He dashed to the bathroom and grabbed a fuzzy bathrobe from the back of the door that was clearly too small now, but would have to do for the moment. He quickly gathered the clothes he'd ripped off minutes ago and tossed them through the open bedroom door, and then he walked over just as a third knock sounded.
The tall, lanky figure of Gene awaited him, fist still raised. As Mary, he had thought Gene was kind of cute but a bit on the awkward side. He was a nice enough guy, certainly, but just wasn't her type. Now though, Mark saw potential in his neighbor, at least in one way or another. An idea started to form in his head as Gene asked him who he was. "I'm Mark," he replied automatically, "Mary had to step out for a sec, but I'm sure she'll be back any minute now. You can come in and wait if you like."
He ushered Gene inside, making sure to surreptitiously close the lid on the box of vials as he passed the table and carry it over into the kitchen. Gene called back from the living room, "Are you her boyfriend or something?" Mark simply laughed, "No, just her cousin from... out of town. My luggage was lost by the airline, so Mary gave me this while my clothes are in the wash. Can I get you something to drink while you wait?" Gene indicated he'd take a can of pop if she had any, and Mark knew that this was his chance. He grabbed a soda from the refrigerator, popped the top and poured a bit down the sink drain. He then quietly turned to the box of vials.
Something about that invigorating change from female to male, Mark was feeling ... fizzy, like he was a tiny bit high or drunk or something. His inhibitions and any guilt he would have previously felt about what he was about to do to an unsuspecting acquaintance were oddly absent. He quietly popped the top of the box and looked over his options... Gene had told Mary that his thesis had something to do with...some animal... their mating rituals or eating habits or... if he could just remember what creature Gene had been studying, he was sure the grad student would thank him once he realized how much insight this could give him into his subject!
Mark raised his voice, trying to act casual "So Mary told me you were studying biology or zoology or something, right Gene?" he heard papers shuffling in the other room as Gene replied "Yes, a branch of zoology, actually. I'm focusing on..."