"Happy Birthday Caitlin!"

I popped out of hiding as Caitlin walked into the kitchen. I expected her to scream a little, but she just groaned and shuffled her way over to the coffee machine. I frowned. I knew she wasn't a morning person, but this was a little ridiculous. She shuffled back over to me and leaned against me as she drank the coffee.

"Alright, sleepyhead. Sit at the table so I can make some breakfast." Caitlin mumbled something and slowly made her way to the dining room table. As I fried up some bread, bacon, and eggs, Caitlin slowly woke up and became more lucid. When I got back to the dining room with breakfast sandwiches, she was wide awake, eagerly waiting for breakfast.

"Finally awake, Your Highness?" She laughed and gave me a kiss on the cheek. "Yeah. Sorry about earlier, you know how I am in the morning. Thanks for making breakfast." I set down the food and pulled up a chair for myself. As we wolfed down the sandwiches, I kept thinking about the present I had prepared.

When all that remained of the sandwiches were crumbs, I stood up. "Wait here for a second. I've got a special present for you." I quickly ran upstairs and took out a small box that I had wrapped the night before, before running back to the dining room. "Open it!"

Caitlin carefully unwrapped her present. "You can tear it, you know. It's not like I'll reuse that wrapping paper." She just rolled her eyes and kept slowly taking the paper off. "I know, but it looks nicer this way." After a long couple of minutes, Caitlin finally unwrapped the gift. "A wooden box? It's pretty, but not what I expected." I watched her roll it around in her hands.

"Cait, try opening the box, maybe." She blushed in embarrassment. Somehow, she hadn't noticed that the box had a seam that could be opened. She lifted out my actual present, a ornate silver necklace. The chains were made of small silver serpents, and their eyes were made from tiny citrine crystals. "Oh my god! It's so beautiful!" She moved to put it on, but I stopped her before she could.

"Wait! That's not an ordinary piece of jewelry. Remember how you told me about how you loved monster girls?"

"Yeah, but I thought it freaked you out since you were really awkward afterwards. What about it?"

"Well, it didn't freak me out. The opposite, actually, I thought it was really hot. So I had this necklace custom made for you. When you put it on, it'll turn you into a lamia."

Caitlin's cheeks flushed a deep red and she bit her lip as she took in my words. No doubt she was thinking about what it would be like to be a monster girl. "That sounds... incredibly hot, honestly. I just have to wear this, right?"

"Right, but its permanent. Just want to make sure you know befo-"

I didn't get to finish my sentence before Caitlin eagerly put the necklace around her neck. It glowed a blinding golden yellow and vibrated for a few seconds before returning to normal. I had turned away to shield my eyes from the glare, but as I looked back to Caitlin, I saw that her pupils had turned into snake-like slits.

I watched as Caitlin's body continued to change. The whites of her eyes turned a rusty orange, while her tongue narrowed and forked at the end. Her canines also grew into fangs as her head deformed, ears receding into her skull as her overall head shape becoming more snake like. Caitlin moaned, and I saw her mouth open far beyond what would be normal for a human. Mottled green scales formed on the bridge of her nose and her forehead. They also grew on her neck, all the way up to her cheeks.

Caitlin continued to moan as the changes spread further down her body. Scales popped up all along her torso, growing down towards her hips. As they grew, her breasts shrank until they were about an A-cup. Caitlin frowned for a second before the next series of changes hit her. Her pinky fingers disappeared as the rest of her fingers became thin and claw-like. Two lumps also formed on her torso, growing into another pair of arms.

As Caitlin's scales grew past her hips, her legs elongated and began to melt together into one large mass. As her tail continued to grow longer, her pussy migrated down her body until it was positioned on the upper third of her new tail, where it began changing into a cloaca. Caitlin squirmed on the dining room floor as her pussy changed.

"Oh fuck, oh fuck, oh my god, it feelsss sssoooo good! Ssshit, I'm gonna cum!"

Caitlin's newly formed cloaca sprayed her fluids all over the dining room floor as she finished transforming. I would probably be mopping that up later, but I didn't care. I watched Caitlin lay on the floor, gasping for breath as she basked in the pleasure of her orgasm.

"So, best birthday ever?" I grinned as I helped lift her off the floor.

"Hmm, I think I can make it a little better~" She flicked out her tongue as she slithered towards me. She must've seen my erection, because she used her lower arms to strip me before opening her mouth impossibly wide, gulping down my dick.

"Wait, Cait, careful with the fangs, don't bite my- Oh fuck! Your tongue is fucking crazy!"

My worried thoughts about having my penis bitten off faded away as Caitlin began twisting her snake tongue around my penis. I felt it coil around my dick as she bobbed up and down along its length, squeezing in rhythm with her movements as she accelerated her mouth across my dick. Her tongue combined with the energetic movements of her mouth had me nearly ready to bust after not even a minute.

"Cait, I'm cumming in your mouth!"

Her muffled moans sent me over the edge as I came. As she slowly pulled her mouth away, strands of mixed saliva and cum dripped from her mouth and tongue, which dangled between my dick and her mouth before breaking away and clinging to her upper body. She gulped down my seed before quickly stripping out of her clothes, which had somehow managed to survive the changes.

"Ugh, sssperm still tastesss terrible."

"Why didn't you spit it out then? Actually, it doesn't matter. I think the birthday girl still needs some presents."

"Mmm, I think sssooo too. I need sssomething tastier after that. Come here." She slithers her way over to the living room, laying her body across the couch. Her tail is so long that only half of it makes it onto the couch, the rest dangling off the side. She opens her arms invitingly as I make my way over.

I embrace Caitlin and she kisses me, her tongue intertwining with mine. I rub her tiny breasts, rolling her nipples between my fingers as they harden, and she returns the favor by tightly hugging me with her four arms. Her clawed hands prick my back, but I don't mind. I continue kissing her for a minute or two before Caitlin wraps her tail around my lower body, guiding me to her cloaca. She uses her lower arms to spread it wide open, inviting me in.

I sensually slide my dick into her dripping wet cloaca, feeling her body twitch with every inch I insert. Her arms tighten around me as I begin slowly fucking her, pinning her body against the couch. I can feel the end of her tail excitedly wiggling around as I continue fucking her, slowly building up speed. The texture of her cloaca is unlike anything I've ever experienced, and the sensation of it pulsing around my dick is amazing. Caitlin's tongue lolls out of her mouth, her face stuck in an expression of pure pleasure, as I stuff her insides.

"Ah! When your dick ssslides into me, I can feel it warm the inssside of my cloaca up! Fuck, don't stop!"

I wasn't planning on stopping, but Caitlin's satisfied moans spur me on and I speed up the pace, thrusting faster and faster as we both near climax. Caitlin screams in pleasure as she cums, and I'm not too far behind her, groaning as I cum as well, filling her cloaca with my seed. Exhausted, I climb off Caitlin as she continues to spasm on the couch, drool coming out of her mouth and cum leaking out of her cloaca. I close my eyes, tired but happy, as I drift off to sleep.

"Wake up, sssleepyhead."

I open my eyes and try to get up, but something's wrapped around me. I briefly panic before realizing that Caitlin has wrapped her tail around my body like an anaconda, completely immobilizing me. She's still naked, and I can feel myself getting hard again as I continue to stare at her body. She smiles as my erection begins poking her tail.

"Bessst birthday ever."