Ruthless Creatures by J.T. Geissinger

Then his finger breaches the oiled ring of muscle in my
behind, and I groan louder, shuddering.
He demands, “Color.”
“Green.”
He works his finger and the vibrator in and out together at
the same slow speed, pressing deeper with each pass until he’s
buried past a knuckle and I’m starting to press back eagerly
against his hand.
He whispers, “So tight. So hot. Fucking hell.”
I pull against my restraints, arching my back. I’m panting
now, spreading my thighs wider.
Watching me, he groans in approval.
He presses his finger in as far as it will go. In my pussy, he
works the vibrator. My clit is swollen and throbbing. My hips
take over and begin a slow, rhythmic roll.
Kneeling between my spread legs, he says in a ragged
voice, “It will hurt at first. Breathe through it. Try not to tense
up. I’ll go slow. If you need me to, I’ll stop.”
Still rolling my hips against his invading finger and the
vibrator, I whisper, “Green.”
He removes his finger slowly, lowers his body to mine,
and pulls one of my knees up farther on the mattress, exposing
me completely.
Then something much larger than his finger nudges at my
entrance.
I gasp and tense, but he doesn’t slide his cock inside. He
gives me a moment to process, stroking the head of his dick up
and down where he wants to go.
“Breathe, baby,” he whispers, fondling me. “Let me in.”
My heart is beating so fast, I can’t catch my breath. I try to
take deep, even breaths, but just end up panting. My nipples
are hard and my clit is exquisitely sensitive, primed from the
vibrator and the dizzying sensations from both front and back.