Dimensional Experiment Gone Wrong

by Blaze-saber

Rating: mature
Tags: Twilight Sparkle (EqG), Alternate Universe, Human, Romance, Drama, Porn, Equestria Girls, Sex, Flash Sentry, Twilight Sparkle
Length: 3762

An experiment that had gone wrong but feels right

Both Twilights from both worlds have been messaging each other for quite some time now. They thought about what could happen if things from their own world travel to the other and what could they turn into when they arrive.

Both Twilights Flash Sentrys have been helping them for a while and there was an accident that sent each other's Flash to each other's world but with a bit of a surprise. And some chemicals in Princess Twilight's side may have caused something heated to happen.

You'll have to read the story to see me how this turns out.

(bestiality warning)

Published 2022-10-22 15:40:01 UTC
Last updated 2022-10-22 15:40:01 UTC

Dimension Travel Test 167: Flash Sentry. Fail or Fun

Princess Twilight Sparkle and Sci-Twi have been talking via magic book after Princess Twilight asked Sunset to give her one because they were both curious about the portal between their worlds. They both talked about how things from Equestria change when something comes through and ends up being something else, like how a pony changes to a human or like how Spike changed into a dog when he came through. That got them thinking about what else could change when something comes through.

Princess Twilight Sparkle examined the mirror portal and discovered a material that created the mirror in the first place in a crystal cavern. Twilight sent some of the materials through the portal to her human counterpart to create her own mirror so they can test out what could he turned into to each other's worlds. The two have been sending a few things to each other for weeks now and they have either come through and changed into something else or vanished and didn't come through. Both Twilights have had some help from their own Flash Sentrys for quite some time now and this time is about to get a little heated up.

Princess Twilight had some chemicals set up on a table as she was tuning up the mirror portal she made on her side as her Flash Sentry came in with a package. "Hey Twilight, I got those things you wanted." He said as he trotted over to her. "Where do you want it."

"Set them over by the chemicals and be careful. Twilight told him as she used her magic to levitate a few tools. "We wouldn't want anything knocking them over." Flash did as she told and after he set the package down, he looked at her with curiosity.

"What are you doing with your side of the mirror?" He asked as she began to work on it.

"I'm just tuning up the voltage and magic within it to see if things from here can make it through without vanishing." Twilight answered. After a few minutes she put down the tools and wiped off the sweat from her brow. "I got to say, this whole interdimensional travel is hard work."

"I just hope you don't go overboard with some things. Flash said with concern. "I was post here to protect you and your brother would kill me if something bad would happen to you while you work on this." Twilight gave a small smile before giving Flash a small hug.

"And don't forget that the two of us are dating." She told him before stepping back a bit. "And I told you before that I'm always careful. Nothing bad is going to happen." She then opened the box and pulled out a few crystals with her magic. "Besides, the me in that world made a feel safe to keep things in check in case something went wrong. So I promise that nothing bad is going to happen." She then checked each crystal before she noticed a ladybug on the light blue crystal and jumped as she shrieked in fear. Twilight accidentally knocked over the bottles of chemicals on the table when she jumped back and crashed into a bookshelf that caused some dust to fall down. The moment the dust hit her nose, Twilight gave a sneeze and accidentally blasted the crystals on the mirror that overcharged it.

Flash ducked under her blast when it nearly hit him before he noticed the mirror getting overcharged. He knew this was not going to end well, so he quickly went through the spilled chemicals and grabbed Twilight before tossing her out of the room. Twilight looked but was blinded by a bright light coming from the mirror that lasted about a few minutes before it died down. "Flash? Are you okay?" She asked as she carefully entered the room as she was worried about him.

"I'm fine, Twilight." Flash answered with a groan. Twilight gave a sign in relief before she trotted to where she heard him. But when she laid her eyes on him, she gasp in shock to see it wasn't her Flash Sentry, but the human Flash. "I just didn't expect something like that to--" When he saw Princess Twilight, he was speechless at first.

"You...you're still in you're human form!!" Twilight exclaimed as human Flash looked himself over and saw that she is right. Twilight then started to babble how it's possible over and over before Flash put his hand over her muzzle.

"Take a deep breath and calm down." He told her before she did exactly what he told her.

"Thanks." Twilight said before a thought just occurred to her. "Wait, if you're here then that means my Flash is..." The two then looked at the damaged mirror. "Oh boy..."

Just before the incident, Sci-Twi and Human Flash was doing some studying on the mirror in her lab after he brought in some tech she requested. "Thanks again for helping with this. It would have taken me forever to get all this." She told him. "I bet you're really excited to see Princess Twilight when we're done."

"Actually me and Princess Twilight are just friends." Flash told her. "We talked about it after her last visit and we both realized that it wouldn't work out considering, you know." He helped her hook up a few things to the mirror. "Oh, how are things between you and Timber?"

"Don't even say his name around me." Sci-Twi grimace. "I never want to talk or even see that guy ever again!!"

"Did you two break up?" Flash asked as Sci-Twi leaned against a wall while she rubbed her arm.

"I was going over to his place to see if he wanted to go see a movie that came out last week." Sci-Twi started to explain. "I opened the door and heard a bunch of noises coming from his bedroom and I walked in on him having sex with...with a SLUT!!!"

"I'm sorry to hear that." Flash said in a compassionate tone.

"You want to know else? After he tried to explain himself, the woman he was in bed with told me he had others before me!" She shouted. "So I kicked him right in the groin and told him we're done!" She then slide down the wall as she began to tear up. "He was such a big jerk and he broke my heart into a million piece." Flash walked over to her and sat next to her on the floor.

"Hey, it's going to be fine." He told as he wrapped his arm around her. "That guy was a major jerk and an idiot if he cheated on you. I mean why would anyone cheat on you? You're smart, beautiful, and have a wonderful family." Sci-Twi wiped the tears from jer eyes before she looked at him. "Just remember that you have your friends to make it through it if you're ever down." Then to his surprise, she wrapped her arms around his shoulders and gave him a hug.

"Thank you, Flash. I really needed to hear that." She told him as he hugged her back. The two of them then stood up before she noticed her mirror portal was acting odd. Her computer then started beeping red as a sign something is going wrong. Flash saw this as well before he knows the mirror glowing bright. He then pushed Sci-Twi out of the way before a bright light covered the room and a small explosion happened. When it died down and she came too, she was covered in different color liquids and noticed that Flash was not here. She got up and looked around before she saw something of very interest: it was pegasus Flash. Many things went through her head when he saw him on conscious on the ground, like how did he turn into a pegasus or many other things. She saw that he was also covered in different colored liquids and thought that he needs some medical help. She carefully picked them up and carried her out of her lab.

Flash regain consciousness and found himself wrapped in a few bandages while laying in an unfamiliar bed. The last thing he could remember was getting Princess Twilight out of her lab before the mirror sucked him in along with a few chemicals that was on her table. Before he could come up with a conclusion, he heard a door open and saw something he had never seen before in his life. A human girl who has the same colors on her skin and hair as Princess Twilight but is wearing glasses and had a towel wrapped around her body and her hair. "Oh good, you're awake." The human girl spoke with Princess Twilight's voice.

"You must be Princess Twilight's human counterpart." Flash theorized when he heard her voice. "So this must be the human world? How come I'm not human and why are you in a towel?"

"Well first off, you've been out for a couple of hours." Sci-Twi told him. "And I asked Princess Twilight about that through the book and my Flash Sentry got sent to her world and is still human there. She thinks the crystals she got along with her magic may have caused a chain reaction and you both got sucked in without changing." She then walked over to a closet door and open it up. "As for why I'm in a towel, I was washing off some liquid that got on me when you came through. Also there were some liquid on you before I patch you up."

"Oh, okay..." Flash said as he already found out that the liquid that was on him and her where the chemicals that was on the table back in his world. He can't tell her that because it might freak her out and what's worse, he has no idea how it would affect him or her.

"Um...I know that you are usually okay with seeing females in your world naked all the time, but could you look away?" Sci-Twi asked him. "I get really nervous when someone is looking at me."

"Oh sorry." He said as he turned his head away from her. "So, is there a way for me to go back or...?" Flash asked before he caught a width of an odd sent in the air. The smell of it alone made his wings stand at attention before he followed it and saw it was coming from Sci-Twi. The sent he caught was that of a mare in heat and it caused his cock to be erect. She had her back towards him as the towels was removed from her body and head so she didn't see his 20 in long cock. Flash was confused because it was 16 in before the sent made his head feel fuzzy.

"We trying to find a way but both mirrors on both sides are damaged and could take a while to be repaired." Sci-Twi told him as she bend down to pick up something and she sigh as she looked at her breasts. She didn't know how, but her breasts have grown into EE size somehow. She didn't have time to think about that right now as she grabbed a pair of purple striped panties. "Right now the princess is trying to figure out a way to send both back considering we have no idea what will happen if we send you back right no--Aaaahhh!!" She felt a toungue lick her pussy before she looked back and saw Flash has his muzzle deep inside her. "Fl-Flash...ah...wh-what are you doing?!"

He didn't answer her has he was too busy eating her out. Sci-Twi had to drop her panties and hold on to the side of the closet door as she let out moan of pleasure. Flash was clearly enjoying her as he never tasted human pussy before. Sci-Twi hanged her head down and caught a glimpse of his erect cock as it was clear he was using his wings to hover while he eat her out. Her legs felt like jello as she felt so much pleasure from his stallion tongue licking her in her walls. It wasn't long before she unleashed her cum into his mouth and all over his muzzle.

"You taste really good." Flash complimented as she fell to her knees. He then realized what he just did and he landed on the floor before slowly approaching her. "I...I'm so sorry. I just got a scent from you and my head felt all--MEPH!" To his surprise, she grabbed his head very quickly and gave him a passionate kiss on the lips. When they pulled back, a string of saliva connected their mouths as they gasp for air.

"That was amazing." Sci-Twi told him in a lustful tone before she picked him up by the flank and start to make out with him again. She then stood up as they continue to make out and made her way to the bed. They gasp for air again when they pulled back before she made her way down to his stallion hood and took off her glasses. "Let me return the favor." She grabbed his and gave it a couple of gentle strokes before she began to lick it. It tasted a bit salty to her but she couldn't control herself as she continued to lick it from the base all the way to the tip.

"Ah...sweet Celestia..." Flash moaned as he was feeling pleasure from Sci-Twi's tongue work on his cock all while she used both her hands to cup his balls. Her tongue then squirrel around the circular tip of his cock as she was getting more of her saliva all over it. She soon stop just when he was feeling close to cum before she crawled onto the bed and laid her back against the backboard of the bed. "I'm guessing this is your first time."

"Ye-Yeah, especially with a horse." Sci-Twi told him as she started to finger herself. "I can't control my body and it feels like it's on fire. I...I need that cock...use me however you want." Flash crawled up to her before he stood on his back legs and slide his cock across her face. He then lined up his cock to her mouth before he shoved his whole length down her throat. Flash then began to buck his hips as he is facefucking her. Sci-Twi moan around his cock as she continued to rub her own clit with one hand while the other was cupping her breast. Flash loves the way her mouth feels around his cock as his thrusts became faster. After a few minutes, she could feel his cock throbbing in her mouth before he unleashed his cum down her throat. She was drinking up every last drop of it before he pulled back and sprayed her face with his load. She yelled a little when some of it hit her eye before he finished. She then used her hands to gather his load and lick every inch of it away.

It wasn't long before she felt him poke her pussy with his cock as his head is between her breasts. "Mmm~ Twi." He moaned as he slowly pushed his cock into her cunt. Sci-Twi bit her lip as his cock entered her and a bit of blood was shown near her pussy as a sign he took her virginity. The two were breathing heavily as they needed time to adjust a little before flash pushed another couple of inches into her. After he put his whole cock deep inside her, he began to thrust in and out of her while she wrapped her arms around his neck. "Mmm, yes!" He grunted as he speed up his thrusts.

Sci-Twi felt that this was odd but was feeling so good from it as well. She knew that having sex with an animal is illegal, but it didn't say anything about a mythical creature like a pegasus. Each thrust he gave her made it hard for her to think straight as she was in so much pleasure. Her tongue started to hang out like a dog in heat as she was loving this so much. "Mmm... yes!! Fuck me you stallion!!" She begged as he granted her wish. Sweat was running down both of them as they were added for what seemed like hours to the two of them before the came together. She could feel womb getting filled up with his cum as her belly was getting bloated up a little.

The fun didn't stop though as she pushed him on his back and started to ride him cowgirl style. The two moaned as she began to bounce on his cock. Flash used his hooves to grab hold of her hips as she ride him while he watched her breasts bounced. He then got the idea of using his wings to thrust up deeper into her with each thrust. Sci-Twi could feel her magic power up as pony ears appeared on her head and wings formed on her back while her hair was being tied up in a ponytail, Sci-Twi had Pony-up as they fuck. Flash unleashed his cum inside her again as her belly was getting bloated up a little again.

He flew up with Sci-Twi on his cock and stopped mid air, allowing Sci-Twi to almost fly off his dick until gravity stopped her right at the tip and pulled her down onto him hard and fast. They did this several times and Sci-Twi was in heaven.

She had a feeling that the liquid that was on them was chemicals and caused them to act like this and added benefit, allowing Flash quick recovery. It only took him a little bit of rest after that event to be at it again, then again and again. All throughout the night, the pair were at it like rabbits and Flash's balls never seemed to empty.

Her belly bloated from the amount of cum getting poured into her and impregnating her. Once they finally stopped, after what was probably their tenth go, Flash was resting on her as his cock was still inside her.

The next morning, Sci-Twi was taking a shower while she let the many loads flow out of her cunt and down the drain with the water. She was lucky that her parents were out of town on a business trip so she's home alone and she wouldn't have to come up with an explanation for this. She then heard the sounds of hooves walking across the floor before the bathroom door opened and Flash walked in with a sorry look on his face. "Do you mind if I join you?" He asked her.

"I don't mind." She answered before letting him in the shower. She then grabbed a bar of soap and began to wash him as a favor. She could tell that something was bothering him and had a feeling it was about last night. "You want to talk about last night?"

"It's just...I'm really really sorry about what happened." He apologized as his ears fell back. "I just didn't know what came over me and it just felt really good that I couldn't stop." Sci-Twi nodded her head in agreement as she knows where he's coming from. "Now I feel really confused. I'm dating the Twilight in my world and I just fucked her human counterpart here. Is it cheating if I did something like that or what?"

"To be completely honest, I don't know." Sci-Twi told him as she washed his wings. "I never really been in bed with an animal before or one that's from a magical parallel universe. And me and my Flash are just friends here." She stop for a moment and let out a sigh. "But after the last few weeks with him, I'm starting to have these feelings for him as he was helping me with the mirror project. If your Twilight and you are a couple, why not me and my Flash?" He looked up at her and gave a smile. "By the way, I talked with her and it's going to take a while before both mirrors are fixed up and we could find a way to send both back."

"Thanks for the update." Flash said before he caught that sent again and his cock became erect. "Oh come on!" He complained before her hand gently grabbed it and stroke it. Even looked up at her and saw a lustful grin on her face.

"I even told her about what happened last night and she admitted that she and my Flash did it as well last night." She told him. "She'll look for a way to reverse it soon. But for now, I rather enjoy having more time with this long dick of yours~. It makes me wonder if my Flash is any good as you, even without the wings." She then brought her lips to his as they began to make out and was ready for another round.

Back in Equestria, human Flash was getting things together in the lab to help out Princess Twilight fix the mirror. He soon heard the door opened and knew it was her. "Hey Twilight, I got everything ready for the mirror. I'll help out anyway I..I..." His words got caught in his throat when he saw her. Twilight was somehow now anthro mare wearing nothing on her body and EE size breasts. "Tw-Twilight...eh...what are you doing?" He asked with a big blush on his face as she approached him.

"Oh this?" She asked as she gestured to her own body. "I found the spell a long time ago but didn't have any reason to use it until now." She then pressed her breasts against his chest as she saw a big bulge in his pants. "And it seems you like it~. Don't worry, I can work while we fuck at the same time." Flash could tell this is going to take a while but he wasn't complaining as the two started to make out.

Author's Note

This story is based off this image: https://e621.net/posts/1272216?pool_id=5081

I thought it looked nice and everything. And before you start hating this, let me remind you all if there's a few stories on here that involved humans and dogs in bed. And this is just a one-time thing.