You and Evelyn take her together.

Together you stride forward, walking around opposite sides of the desk perfectly in sync. She looks frantically from you to Evelyn and back again, pulling her arms in to protect herself.
"No, no, no..." She whispers. Evelyn grabs her wrists from behind and looks at you. You nod, reach down and grab her ankles. She squirms between you, kicking her legs violently. But your vampiric strength is far too great. You move her over and dump her on the desk, legs dangling off of your end, breasts facing the ceiling. Evelyn leans forward and pulls Diane's top over her arms and head, revealing her braless chest. Her tits quiver as she sobs, the pink, perfectly sized nipples jiggling attractively. Evelyn climbs up on to the table an kneels just above Diane's head. She leans down and kisses her tits, sucking at her pretty nipples passionately, fixing you with her crimson stare the whole time. With that, you pull down Diane's shorts, to reveal that she wasn't wearing panties either! Her pussy is shaved and perfectly formed at the end of her V stomach lines. You massage her thighs, then move your rotating thumbs to her labia. You look up to see that Evelyn is grinding her wet cunt into Diane's mouth. You decide to mirror this, shoving your tongue deep into her pussy hole, teeth pressuring her clit carefully. You try to stay to the girls rhythm, continuing to keep eye contact with Evelyn while you do. Soon, Evelyn and Diane reach climax, Diane first gurgling as she tries to release her orgasmic screams, then Evelyn, who drips her juices into the woman's spasming mouth. Evelyn smiles at you and slides closer, grinding her cunt over Diane's soft tits. She reaches down and pushes your penis into Diane's hole. Diane shudders and writhes, all tears replaced with moans of pure ecstasy. You begin to massage her cunt with your cock, making sure to go slowly. Evelyn admires your work, and even grabs your buttocks to pull you in while kissing you fully on the mouth. Then she slides back over Diane and lifts her up, scooting in behind her so that the woman rests on the vampire's wet vulva. She teases her ears with her fangs and fondles her breasts, but now you also have another hole to chose from. You jam two fingers into Diane's sopping vagina and shift your penis to Evelyn's waiting hole. She moans as she licks up the length of Diane's neck, who is fast approaching climax, judging by her rapid, high-pitched squeals. You shoot a load into Evelyn, then switch to Diane to finish the job. Now you are pounding like a jack hammer, the vibrations shaking the table dangerously. Diane is tossing her head about, screams and moans escaping her lips in intermittent bursts. You lean in close, easily keeping up the demonic pace, and bite deep into her neck as Evelyn takes the other side. As the blood rushes into your mouths you come hard with Diane, shooting load after load into her tight cunt. Diane quivers and shakes, only held on the desk by you and Evelyn's strong grasp. You feel her squirm between you, then tire and subside. You pull your fangs free and gaze over the sleeping beauty. You see Evelyn has a little dribble of blood on her cheek, so you lick it up and kiss her passionately at the same time.
"Mmm you taste good..." She says. You pull out and admire your handiwork. Diane's vagina is leaking cum all over Evelyn. You press her labia and more comes out, caking the goth girls pale thighs and pussy. You cast your eye over Diane as she awakes. Her tits are some how larger, her muscles more defined and her ass feels firmer. The best changes of course are her neon blue eyes, pale skin and razor sharp fangs, which you see as she yawns. She smiles at you devastatingly, her beautiful white blonde hair flopping over her face. You lean in for a kiss which is met with great passion. You pull back to let Evelyn have a go. As they embrace you see Diane scoop up the cum from her pussy, then when the girls' lips are no longer locked together, she samples it hungrily, wiping the remainder on her voluptuous breasts, all while staring you dead in the eye. Truly she is some thing remarkable.
"Thank you for this perfect gift." She says earnestly, returning to kiss Evelyn with her cum-stained mouth.
"Any time." You say smugly.