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Star Sex: Pilot

The gaster has merged without any complications." "g-gaster?" she placed her hand on his shoulder. "i should explain. first, let me introduce myself. i'm doctor cand-e." "hey, uh, i'm jack." "it's a pleasure to meet you, jack."

Alien, Anthro, Bug, Eggs, FTM, Female, Gender Shifting, Hyena, Insect, Male, Masturbation, Monstergirl, MtF, Oral, Oviposition, Ovisposition, Pseudopenis, Sci-Fi, Sex, Transformation, feminization

Reports Of A Grey Door

I'm gaster..." gaster said, peeling off alphys's clothing. alphys blushed deeply, becoming more sensitive. gaster began feeling around alphy's skin, making her moan slightly. gaster squeezed her breast, alphys moaned loudly.

Alphys, Blaster Gaster, Cum, Deep Throat, Doggystyle, Erection, Female, For Research, Gaster, Heat, Hotland, Kissing, Knotting, Lab, Magic, Male, Mating, Oral, Orgasm, Rape, Sex, Sexual, Story, Studing, Undertale, Waterfall, instincts, research, scientist

Alphys' Modern Life: Camera Shy (Part 1)

The three of them screamed their brains out as they suddenly saw gaster chasing after them, prompting them to immediately take off running as fast as they could! "alphyyys' moddderrrn lifffe!"

Abuse, Adorable, Adorkable, Adult Content, Alphys, Anal, Anime, Anthro, Asgore, Asriel, Bestiality, Bisexual, Blood, Blush, Bondage, Breastfeeding, Breasts, Burgerpants, Canine, Caprine, Cartoon, Cartoony, Cat, City, Comedy, Creampie, Crossover, Cum, Cumshot, Cunnilingus, Cute, Dancing, Dog, Ears, Ejaculation, Eldritch Abominations, Endosomatophilia, Erection, Erotic, F/F, Fanfiction, Fantasy, Feet, Femdom, Fetishes, Fighting, Fish, Flowey, Foot Fetish, French Kissing, Giant, Glasses, Goat, Godzilla, Horns, Humiliation, Humor, Incest, Insanity, Kissing, Lesbian, Licking, Lizard, Love, M/F, Macro, Masturbation, Memes, Menstruation, Messy, Mettaton, Mind Control, Monster, Musical, Naked, Naughty, Nickelodeon, Nudity, Odors, Oral, Orgasm, Papyrus, Parody, Pheromones, Police, Porn Flick, Pornography, Posing, Prison, Public, Pussy, Rabbit, Relationships, Reptile, Robophilia, Robot, Rocko's Modern Life, Roller Coasters, Romance, Rule 34, Sans, Satire, Scalie, Semi Consensual, Sex, Sexy, Shrinking, Singing, Size Difference, Skeleton, Song Parody, Suicide, Tail, Tailhole, Teasing, Tits, Toriel, Undertale, Undyne, Vaginal, Video Games, Voyeurism, WORSHIP, brains, cameras, dating, dinner, drooling, embarrassment, giantess, gross, moaning, privacy, shipping, skiing, spaghetti, toes

Alphys' Bad School Day (PART 3)

"why, gaster? why are you doing this to me?"

Comedy, Fanfiction, Romance, Undertale

An Experiment Gone Wrong? CH.4 (Rewrite)

Your first day visiting gaster laboratory is very nerve racking. gaster was not happy working around asriel, but knew this was the only way you'd agree to allow him to run any test.

Asgore, Asriel Dreemurr, Frisk, Gaster, Hurt/Comfort, Named OC, Papyrus, Sans, Toriel, Undertale, Undertale AU, Undyne, chara

An Experiment Gone Wrong? CH.8 (Rewrite)

gaster raises a hand, "i think i see where your going with this. you made an unauthorized visit out of mt. ebott and acquire these items during that trip."

Asgore, Asriel Dreemurr, Frisk, Gaster, Hurt/Comfort, Named OC, Papyrus, Sans, Toriel, Undertale, Undertale AU, Undyne, chara

Hidden

Alex felt almost like a turtle on his back as he landed on his wings and gaster, but he gasped even wider as fargo crawled on top of him and began to move in.

Alien, Anal, Dark, Gay, Insect, M/M, M/solo, Oral, Oviposition, Sci-Fi, Transformation, Wasp, infection, paralysis, self suck, tf

Alphys VS Undyne

The three of them screamed their brains out as they suddenly saw gaster chasing after them, prompting them to immediately take off running as fast as they could! "alphyyys' moddderrrn lifffe!"

Abuse, Adorable, Anal, Anime, Anthro, Bikini, Bisexual, Breastfeeding, Breastplay, Comedy, Cum, Cumshot, Cute, Dancing, Domination/Submission, Ear Fetish, Ejaculation, Erection, Family, Fanfiction, Female, Femdom, Fighting, Fish, Foot Fetish, French Kissing, Friendship, Gang-Rape, Gay Relationships, Genital Vore, Glasses, Handjob, Humiliation, Incest, Insanity, Kinky, Kissing, Lesbian, Licking, Lizard, Love, Masturbation, Mermaid, Mind Control, Nudity, Orgasm, Parody, Public, Rape, Reptile, Romance, Satire, Scalie, Sex, Singing, Soulmates, Strangulation, Striptease, Tail, Teasing, Tentacles, Tickling, Underwear, Vaginal, Video Games, Vore (soft), Voyeurism, Wrestling

Heroes of Hopes and Dreams

Sans yelled just as the two gaster blasters opened their maws and fired.

Action, Comic Book, Epic, Fighting, Human, MLP, Mettaton, Music, Ocellus, Papyrus, Robot, Sans, Smolder, Undertale, Undyne

Alphys' Bad School Day (PART 2)

Papyrus yelled to get sans' attention as the latter was surrounded on all sides by muffet, gaster and temmie! "oh no, you don't!"

Comedy, Fanfiction, Romance, Undertale

An experiment gone wrong? Part 4

Having gaster run test on him would be the same and it would just open the gaping wound in soul more. if, and only if he agrees to it will i allow it, but if he refuses then this subject with gaster is closed."

Asgore, Asriel, More characters to come, Original Character, Toriel, Undertale

An experiment gone wrong? Part 5

You also picked up some basic cell phones for everyone figuring that gaster could do something to make them work in the underground.

Asgore, Asriel, Gaster, Original Character, Sans, Toriel, Undertale, chara