You remember the door code. Rush him!

As a more senior member of the management team, it's your job to remember important things like the door code for the records room.
"Bob please." You say, trying to distract him as you punch in the code.
"I-I'm sorry but- Hey what the fuck!" He yells as the door opens. You rush in, your speed suddenly growing as your transformation takes hold.
"Sorry Rob, I am one of them!." You reach forward to grab at him, but are pushed back by a searing pain in your palm. You screech and look at your hand, seeing a cross shaped burn in your right hand, which is already pale and taloned. You look up; Bob is holding a small wooded cross on a rope.
"S-Stay back, you monster!" He says, his voice quivering. But you have a secret weapon. While the right side of your body is quickly changing, your left hand is still very much human. You rush forward again, but this time you grab at him with your left. He yelps as you grab the cross easily and toss it into a corner, then you grab his greasy shirt with your vampire hand and lift him into the air.
"That. Hurt!" You say, and throw him to the ground. You breath in deep for the last time as your transformation takes hold. You undo the buttons of your shirt and trousers letting the clothes fall to the ground in a heap. You run your now taloned hands over your muscular, perfect body, feeling the hard perkiness of your breasts and the strong, firm muscles on your abdomen and thigh. You run your long tongue over your sharp fangs, and glare down at Bob with your now more than perfect eyesight. He whimpers and tries to crawl back, but you only smile. You pounce forward, wrapping your red lips around his sweaty neck. You drink messily letting the warm, tasty blood spray you and the record room. It doesn't take long for Bob to go limp. You arch up, letting out a sigh of satisfaction. You look down at your bloodstained body with grim pleasure.
"Sarah?" You hear behind you. You stand and turn to see Keira, your friend and colleague. Her transformation has done her wonders. Her shaggy, dull blonde hair now sits in a golden haze around her sharp face. Her non existent breasts are now round and ample, sticking out dramatically from her bare chest. Like you, she is completely naked, however, you see her hungry eyes exploring your blood caked body. You step forward, putting a hand to her cheek.
"Please." You say. "Drink." She wastes no time. Starting from the gore on your chin, she works down, lapping hungrily at your neck, collarbones, breasts, abdomen, and, finally, your crotch. She takes the blood around your waiting cunt, teasing you. Finally, when you can take it no longer, you grab her head and smush her face into your clit. Keira gurgles but pleasures you happily. You begin to moan in ecstasy. You notice a rustle behind you, and feel Robert's sharp fingered hands brushing your shoulder blades. He circles around in front of you, showing his devilish new smile. His beer belly is replaced with a hard six-pack and pecks and his erection is a foot and a half long. He lifts Keira up by the hips, then plunges his length inside of her. The girls barely pauses, but soon you can hear her moans as he thrusts his massive cock inside her vigorously. The three of you begin to move in unison, you grinding against Keira's flailing tongue, Keira's pulsating efforts in both her vagina and mouth, and Roberts hearty thrusts. Keira comes first, with you following soon after. You collapse, Keira resting on you as Robert finishes, his cum arcing over Keira's writhing back. Then he rests too, sighing deeply with satisfaction. Keira takes a moment, then looks up at you, crawling in for a long kiss. You look over at Robert who flashes you a hungry grin. You look up to see Theresa and Beth watching from the door.

"That was quite a show." Theresa says. "Would you care for some refreshment?" Beth extends a hand to Robert, who accepts it and stands to his feet beside her. You rise with Keira. The five of you head off in search of warm bodies to sate your lusts.