Illya gets her turn with Shirou

A/N: Illya has been aged in body in the previous chapter. She is now 18 years old in both body and mind.

It is a rare day when Shirou Emyia has a quiet house, all to himself. Today is one of those days. Gentle patters of rain drops meet the window, but as you begin to relax, there is a gentle knock on your front door.

You open the door to see a white-haired, red eyed girl standing before you. She wears a dark purple blouse, accentuated with white dress and white stockings which trail up her slender legs.

"Hey, can I help you?" You ask. The girl responds with a grin. "What, you don't recognize me, Onii-chan? I'm all grown up now, and it's time to play." Your eyes lock with hers, entranced. As you stand there slack-jawed in Illya's mystic eyes, she guides you onto the couch and sits you down.

Illya releases part of her hold on you, allowing your arms, hands, hips, and head free movement as she slips off her panties. "Like what you see?" Illya teases, flaunting her ass out at you. "Illya, you're -" you say before Illya cuts you off. "All grown up now. So I can finally have my way with you." She says as she slips your boxers off, watching your cock spring to life.

Illya grins. "I always knew you wanted to fuck your little sister, Onii-chan. How lewd. Hu, hu, hu~" Illya laughs as she licks your cock. She kneels down in between your legs and takes your cock into her petite mouth, reaching up to grab your hands and place them on her head.

You moan in the pleasure. Illya doesn't have the experience of Rider nor the bosom of Liz, but her enthusiasm knows no bounds. Her hair feels like silk in between your fingers as she lubricates your cock with her saliva.

With a pop, your cock exits Illya's small sucking mouth. "Looks like we're all ready down he-ere!" Illya sings as she slinks up your body, deliberately sliding your cock along the silken fabric between her breasts. She opens her legs as you feel your cock sliding down her white dress, finally popping free and erect, lining up with her tiny entrance.

"I'll give you one chance to enjoy this with me, onii-chan." Illya's eyes narrow as her lips twist into a grin. "If you want to resist, then I'll just freeze you again and have my way with you." Illya lowers herself on to you so your cock brushes against her pussy as it comes to rest on her skin.

She snaps her fingers and you can move again. "If you want to cooperate, all you have to do is give me a kiss, and put your hands all over me." She says with a grin, leaning her lips into you as she grinds her hips against yours.

You don't even need to consider your options. You swallow your nervousness and lean forward to meet Illya's lips with your own. Your hands slide up Illya's stockings and up her skirt to grasp the soft skin of her butt. As you kiss, Illya slides herself back up, always keeping your cock head pushed against her tender body.

You feel yourself teasing Illya's entrance, the heat already radiating into your cock. Illya shivers as she slowly lowers herself onto your stiff rod. You feel resistance about half way in and pull her firmly onto to your cock, hilting you fully inside her. Illya gasps with the pain, you move your hand to rub her back and wait for her to recover.

Illya breathes raggedly as she begins to move and the blood trickles down your cock. The pair of you continue to kiss and fuck slowly as you move your hands down to her small hips. Her petite pussy feels so good.. Almost as if it were made just for you. It's not a supernatural feeling, like Rider, nor a artificial one like Liz. It feels comparable to Rin, like a human, but more velvety, soft, small, and tight.

Illya moans, "onii-chan!" As she shudders from her first orgasm. "Illya, I'm gonna cum...!" You exclaim. She places a finger at the base of your cock and casts a spell. "Nuh-uh. Not yet." You feel your cum building up inside you, waiting for release as Illya rides your cock harder.

You meet Illya's passion with your own. Your tongues dance with each other as you kiss, the lecherous sounds of your coitus squelching in the house. You grip Illya close, pulling her into you. "Onii-chaaan!" Illya calls over and over as she trembles with her orgasm.

Your cock is hard as steel, and the pressure of your cum nearly too much to bear. "Are you ready, onii-chan?" Illya asks as she sinks you into her. You nod and bite your lip. She places a finger on the base of your cock once again and releases her spell as her tight, wet hole grips you hard.

You clench and squeeze Illya's ass against you, pulling you deep inside as a torrent of cum explodes inside Illya. A red flash of a magic seal appears on Illya's stomach as her pussy sucks in all your cum. Illya grins, gives you a kiss, and places her hand on her belly. As your vision begins to fade, Illya leans into you and whispers, "Congratulations, Daddy."