What the deuce are you looking at?
I wake up to see the sky. Weird. I look around and notice I'm a puddle of goo. What the hell happened last night? I look around and notice I'm in a forest. A pony walks by and stares at me. I do the only reasonable thing. I say

I slither away and consume some small animals. I end up in the Crystal Empire and decide to see how everypony's doing. I slither up the palace wall and see a familiar sight.

Oh god. Oh god oh god oh god. I'm going too! WOOHOO! I leap into Twilight's saddlebag. Nopony suspects a thing! OH GOD! I feel sick! Must be going through. I wake up and see Twilight about to scream. I cover her face with myself.
"What's that?" Spike asks.
My head pops up and I say "I am a Symbiote. A being from a world which is not Equus or Earth, the planet we are on, and I can help you with this predicament." I crawl up to the top of Twilight's head.
Twilight asks "How? You're not from this world."
"I used to be a human, the being you have transformed into, and then I got stuck in Equestria as a Symbiote. You have been transformed into a human because magic is not a thing in this world. Unicorns and Pegasi are myths here."
"Wait, if you got stuck in Equestria, how are you here?"
"I sneaked into your saddlebag. I have an easier way to explain." I crawl into her ear and connect myself to her brain. I transmit all my memories of the human world to Twilight's brain. I crawl out to see Twilight knocked out. "Spike, don't talk. You have turned into a dog. I will just get some energy while waiting for Twilight." He nods. I crawl over to the fountain to see human Fluttershy with a bird on her shoulder. IDEA! I crawl up Fluttershy's back and eat the bird. Fluttershy see's a feather fall and gasps. She looks up at me and I change my form into a Pikachu, with colour and all.
She says "You're big for a mouse."
I complain by saying "I'm a human."
"Really?"
"Yes, it's me, Scarred Blood. I just need to consume more things before I can fully regenerate. Oh, my sister's waking up. She got knocked out. Bye!"
"Bye." I change my form into a bat and fly over to Twilight.

"Twilight!"
Twilight looks at me and says "Oh, hey Scar."
"Okay, in this world, you're my sister. Not Shining Armor's. Okay?"
"Okay. What do we do now?"
"We go to my house."
"Okay." We arrive at my house. I open the door and crawl in.
"Hey, Hawkeye!"
"Squawk!"
"I have a pet eagle." Twilight walks in and sits on the couch.
"What now?"
"I show you my stuff." I crawl into the kitchen. "Here is the kitchen." I consume everything and change my form to a human's. I walk over to a room and open it. "This is my bedroom. Bob and Hawkeye sleep here as well. Bob!" A creeper walks up to me. I stroke it's head. "Anything happen while I was gone?" He nods and hisses happily. I walk with him to see a box. I open it to see a PlayStation 3. "Oh yeah!" I close it and go over to the next room. "Here is my secret collection. Don't tell anybody or pony." She nods. We walk in to see a collection of weapons. I have a spear, a halberd, a collection of knives, a battle axe, Mjolnir, a flail, a collection of katana's, a javelin, some dynamite, a block of TNT, a lighter, several boomerangs, a musket with a bayonet, a crossbow, a bow and arrow, a blowgun, a blunderbuss, a raygun, a cannon, a training dummy, an FG42, a Panzerfaust, a Luger, an Iron glove-like weapon, Galvaknuckles and a selection of different grenades. We go to the next room, which is the garage. "This is the garage." I have the DeLorean from Back to the Future, the Aptera 2e, a Lexus 2054, an Audi RSQ, The MADMobile from Inspector Gadget, The Batmobile, a Ghost from Halo and a Bugatti Veyron.
"Next we have the backyard." Godzilla, Anguirus, Mothra, Mecha-King Ghidorah who has retired destroying planets, Rodan, Ebirah, Giamantis, Minya, Spiega, Gorosaurus, Manda, Baragon, Varan, Gabera, Gigan, Megalon, Mechagodzilla, Titanosaurus, Biollante, Battra, M.O.G.U.E.R.A, Spacegodzilla, The Destroyer, Meganguirus, Zilla, Monster X, Gyaos, Irys, Goliath and M.U.T.O are all in my very, VERY big yard. "Here we have my bathroom." Just a standard bathroom. I walk to the roof with Twilight. "This is the roof. It has an airfield on top." I open all the hangers to see a fighter jet, a UFO, an SR-71 Blackbird, a stealth bomber, the Planet Express spaceship from Futurama, a space shuttle, an X-Wing Fighter, the Ark, a Banshee from Halo, a Geonosian Solar Sailer, a Lambda Class Shuttle, the Moldy Crow from Star Wars, the Fireball XL5, the Lexx, the Prometheus, the Gunstar, a UD-4L Cheyenne-class Dropship, a SHADO Interceptor, a TIE Fighter, the Slave 1, an SA-23E Mitchell-Hyundyne Starfury, the USCSS Nostromo, the SSV Normandy, the Starbug, the Heart of Gold, the Colonial Viper, the Defiant, an Eagle Transporter, the Liberator and the Serenity. On the helipads we have the Blue Thunder, the Airwolf, a Scorpian from Avatar, the Bat from The Dark Knight Rises, the Bubbleship from Oblivion, a Z-10, an MI-24 Hind, an AH-2 Rooivalk, an AH-1W Super Cobra, an A-129, an AH-1Z Viper, a Eurocopter Tiger, an MI-28H Havoc, a Kamov KA-50 and an AH-64D Apache Long Bow. We walk to the basement. "This is the basement." It has the TARDIS in there, the Stargate, some machines and my guitar.
I go into the TARDIS and motion Twilight to follow. She gasps at how big it is on the inside. "How is it so big on the inside?"
"Nobody knows...Well, this is a Time Machine. You can also travel through space with it." I set the TARDIS to travel to my space station. We travel there and we get out. "This is my space station."
"Oooh, Aahhh."
"Yes, quite. This is the hanger." There is the USS Akira, the USS Gryphon, the USS Rabin, the USS Thunderchild, the USS Geronimo, the USS Leyte Gulf, the USS Dakota, the USS Devore, the USS Summit, the USS Adelphi, the USS Ambassador, the USS Enterprise, the USS Excalibur, a Valley Forge, an Engineer's Ship from Prometheus, an Asgard Ship, the Romulan Warbid, the SSD Executor, the USS Sulaco, Space Battleship Yamato, the Event Horizon, the Talyn, the Destiny, a Vorlon Cruiser, the Andromeda Ascendant, the Cygnus, a Borg Cube, the Voyager, the Discovery One, the Klingon Bird of Prey, a Star Destroyer, the White Star, a Shadow Ship, the Red Dwarf, the Moya, the Battlestar Galactica and the Millennium Falcon.
"Wow. You have a lot of things."
"Yes I do, now let's get to earth and get you into Canterlot High... we forgot about Spike!"
"OH NO!"
"Don't worry. We will just go back to the exact time we left."
"That's a perfect idea!" We get into the TARDIS and go back to earth. We get into the DeLorean and I fly us to Canterlot High.
We see Spike there and Twilight goes to him. I say "You might want to hide him. No animals in school." She nods and puts Spike in her bag. I take her to Principal Celestia's office. After we were finished with that, we go to the assembly hall.
"INCOMING!" is the first thing we hear when we get in. I form into an umbrella and Twilight holds me. Confetti rains down on us. When we were done with the party nonsense, Twilight and Spike left. I changed into my Symbiote form and then Sunset Shimmer came in. I crawl up to her neck and control her. I make her tell the truth about getting rid of our friendships. Then I consume her.
I change into my human form and Applejack asks "What just happened?"
"I ate Sunset Shimmer."
"Why?"
"She tried to ruin our friendship, but we will always be friends." I change into a Mew and teleport into Twilight's back. Spike's about to scream so I put a paw over his mouth. "I ate Sunset Shimmer, we have no competition." An exclamation mark appears over his head. I teleport to the Principals office and change back to my human form. I walk in and say "Sunset Shimmer has moved school, Principal Celestia." If I tell her Sunset Shimmer is dead, that wouldn't be very smart. She'll kick me out!
"Okay, Scar. I will inform everybody later, thank you for telling me."
"Of course." I walk out and change back into a Mew. I teleport back into Twilight's bag. "Spike." I whisper. He looks at me and I say "What's happening now?"
Spike says "We've just got back to your place." I teleport into the TARDIS and change into my human form. I left a note on Twilight's bag. I travel to the time Twilight goes back to Equestria. I get out of the TARDIS and notice I have dragon wings. I get into my DeLorean and fly to the school. I land and wave goodbye to all my friends. I drive through the portal. I wake up to see everypony staring at me. They gasp at my eyes. I do a repeat of my earlier saying.

I notice my DeLorean a few feet away. My hoof forms into a button and I press it. The DeLorean drives to me. I use it to help me get up. "Who are you and what happened to you? You look absolutely hideous!"
"Buck you too, Rarity."
"How do you know my name?"
"Each and everyone of you guys have a version of yourself in that mirror. I advise NONE of you go in there."
Twilight says "But Scar, you can't go back now."
"I know, that's why I'm going back in time."
"BACK IN TIME?!" All of them shout.
Twilight asks "But how? Your TARDIS isn't here."
"I got this baby!" I bang my hoof on the hood.
"That's a flying car."
"If you go 88 miles an hour you can travel through time."
"Oooooh." I grow a horn and levitate it outside.
My horn disappears and I say "Well, I'll see you three years ago."
"Why?"
"You'll see." I fly into the DeLorean and wave goodbye. I set the destination to 90 million B.C. The first thing I see is a creature that looks like Ahuizotl. I consume it. I am HUGE. It looks like I'm just a neck and head sticking out the ground. I consume a centaur, a pack of cerberus, a chimera, several cockatrice, a cragadile, a draconequus, a full grown dragon, a hydra, several manticore, around 50 parasprites, a phoenix, a quarray eel, three sea serpents, a tatzlwurm, a pack of timberwolfs, a family of Ursa Majors, a pack of windigos, some gargoyles, a giganotosaurus, an albertosaurus, a t.rex, an argentinosaurus, and a herd of buffalo. I change back into pony form and go further back. I consume a three headed dragon, a divine moth, a giant pteranodon, a giant alien cyborg, an irradiated godzillasaurus, and a few small creatures that got in my way. My head is in the clouds. I go to the time the pony tribes were doing stuff.
They all saw me and screamed. I change my form into my pony form. I go to all three leaders of the tribes, and explain that a creature has come. I told them they should archive all information on it. I make a sketch of my normal form, and say that it's humongous, it can change form, can possess other creatures, and is apparently peaceful. I go to the DeLorean and travel to Twilight's first Hearth's Warming. I take a photo of me and put it in a box. I put a piece of me in there as well, but in a vial to keep it safe. I put a shark tooth in there. I put a label on the vial saying 'Don't Open!'. I wrap up the box and write on a label 'To: Twilight Sparkle. From: A Future Friend.' I sneak into her room and put the box on the floor. I travel to the time the first episode of MLP took place.
Author's Note
Yes, I killed Sunset Shimmer. DEAL WITH IT! Oh, and my OC is called Scarred Blood.