Note: Star vs the Forces of Evil belong to Disney and Sonic the Hedgehog belong to Sega. I don't own anything, and again this is my first fanfiction, so my story is not perfect. But I hope you enjoy my crossover fanfiction. Now let the story continue.
Sonic and Star in Adventure in Mewi
Chapter 1 - The Fastest Thing Alive Meets Star the Underestimated
Meanwhile at Neo Scrap Brain Zone, Eggman's secret hidden mountain base on New Mewni, which is based on Eggman's original Scrap Brain Zone back on Mobius. We find Eggman in a giant, dome shaped room overseeing his robots placing the Master Emerald on top on a metal version of Angel Island's Emerald Altar at the center of the room which design to use the energy of the Master Emerald to power the whole Zone.
"Step one, stealing the Master Emerald to power my Neo Scrap Brain Zone and my Emerald Locator Radar. Now Seth we began with step two." said Eggman talking to a large Septarian as the Master Emerald is connected to the metal altar. "Even if we use the Master Emerald to restore the wand, we still need to find and gather all 7 Chaos Emeralds so we can be invincible and for our plans to succeed without a hinge."
Seth, a large Septarian with a face resembles of a crocodile, white hair, buff muscles and wore black jeans and boots replied in a deep voice "a well thought out plan Dr. Robotnik, soon if our plan works, you will rule Mobius and I shall rule New Mewni."
"Indeed, and after 3 weeks of studying both the wand and the giant armor your warriors brought back, you and I would be emperors of two empires."
Then a robot holding a red rectangle device entered the room and walk beside Eggman and said "Dr. Eggman, a small Septarian scouting team in Blue Hills, the team Seth sent, has reported back, they found a Chaos Emerald."
"Excellent Egg Pawn #8763"
"But Dr. Eggman the Septarian scouts also say that two humans have grab the Emerald before them."
"What?" said the mad scientist, as he and the Septarian leader turn to face the robot. then the egg pawn handed Dr. Eggman the device which show a picture of two teenagers as one of them climbed a tree and grab a white Chaos Emerald.
"Those fools don't know what they gotten their selves into. Order the scouts to get the Emerald from those teenagers. Then report to me of the operational status of my Emerald Locator Radar." ordered Eggman and the Egg Pawn respond with a salute and walk out of the room. Then Seth turns to Eggman and asked "Doctor, you said we need to gather all 7 Emeralds, other than the Emerald I found which brought me to Mobius, there are only 5 Emeralds here on New Mewni, so you think this Hedgehog could have a Chaos Emerald and if so, should we send our army to get it?"
"That won't be necessary, if I know Sonic and his friends, he'll find a way to New Mewni, so all we have to do is wait and see." answered Eggman as he began to leave the room "in the meanwhile, I'll prepare my Egg Mobile for battle and head towards Blue Hills just in case. as Eggman brush his long brown mustache.
Meanwhile in Blue Hills on the same planet, Star Butterfly, former magical princess of Mewni, now normal teenage girl stare at the white gemstone alongside with her best friend and boyfriend, Marco Diaz. It's been 3 weeks since Star destroy the Realm of Magic to save every monster on Mewni which also accidentally fuse two worlds which created New Mewni, since then Star and her friends and family began to live a peaceful life while helping everyone around Echo Creek to adjust to their new life on New Mewni. Although there are still some people blame her for ruining their lives, but other than that, it was peaceful, until last week rumors began to spread of Septarian who still view her former royal family as enemies since the time of Solaria Butterfly, started to rebuild their army and began searching for mysterious gemstones called "Chaos Emeralds" which rumors hold magic powers.
"So, this is a Chaos Emerald?" said Marco while holding his hands in his red hoodie jacket pockets "it doesn't seem impressive other than the Emerald itself. Do you really think this Emerald hold magic powers Star?"
"I hope not" answered Star as she remembers her last experience with magic. "We really don't' need someone using magic to create an unstoppable army. Especially when we are still adjusting to our new lives." Then Star put the white Emerald in her star shaped bag unaware that the Emerald does have powers and a Septarian scouts are secretly following them waiting for the right moment.
Meanwhile at the over side of Blue Hills. Sonic, Tails, and Knuckles appears from the portal and reach their destination and stare in awe at the blue colored grass, the hills, and trees. To Sonic it's remind him of Green Hill Zone back on Mobius but with a more mystic feel to the surroundings. In a distance a city that looks like a fusion between modern buildings and medieval buildings.
"Ok now this is unexpected." Said Sonic as he can't wait to see what this world has in store for him.
"This is strange" began Tails as he points at the city in the distance as he still holds his M.E.D.E.L device in hand. "The city looks like modern day buildings found on Planet Earth, but I can also seem medieval buildings you can find in a fairy tell story."
"Right, now that we're here, what's our plan." asked Knuckles which Tails answered "well I guess if we find another, so we can boost my device's range and scans since the Chaos Emeralds do draw to each other, we can use that to our advantage." then Tails began to use his device to do a range scan and located a Chaos Emerald which surprised him "Strange I couldn't get an exact location before, but now I have? I guess because we're here and the Emerald is closest to us?"
"Let's figure it out later Tails, right now there an Emerald closest to us and we need to get it before Eggman does." pointed out Knuckles which both Tails and Sonic agreed and ran towards the Emerald's location. As they get closer to the Emerald's possible location, they began to hear noises of a fight happening in the same direction our heroes are heading. Sonic hand gesture to his friends to slow down and hide behind a hill and see what's happening and that they saw are Septarian Warriors fighting against a teenage girl with fair skin, light blue eyes and long blonde hair that goes down to her knees in sea green short sleeved dress punching a Septarian in the chin and a teenage boy with tan skin, dark brown hair, brown eyes and a mole on his right cheek in a red hoodie jacket, dark gray skinny jeans and sneakers as he karate kick another Septarian in the stomach. The human teenagers seem to be holding on their own very well, but it seems that they could use some help.
"Whoa, they sure know how to fight, but it looks like they can use some reinforcements." whispered Sonic and he rush in before Tails and Knuckles could even speak. Back to Star and Marco, they were holding their own against an Septarian ambush when suddenly a blue blur appears and began knocking out lizards faster than Star and Marco could. "What the." said Star with a confused look as she and Marco stare in awe as the mysterious blue blur continued to knock out more Septarian Warriors. Then a Septarian shouted "retreat" and the Septarian began to flee. finally, the blue blur disappeared and appeared an anthropomorphic blue hedgehog with green eyes and wear white gloves and red shoes with a white strap, cuff and gold buckles each. "Are you two alright?" asked the Hedgehog as a red echidna with large white, mitten-like gloves with two spiked knuckles on each hand and wear red, yellow and green shoes. then to Star and Marco surprise, a two tails yellow fox with white gloves and red and white shoes and in the fox's hand a device.
To Star and Marco, they never see monsters like them before and then Star finally spoke. "Thanks for your help, I'm glad you show up, but I never see monsters like you?"
"Monsters? is that's offensive for someone to just help you humans, I'm Sonic the Hedgehog" Introduce the Hedgehog, offended but he seems to know that Star didn't mean to call him a monster.
"Oh no she didn't mean it like that Sonic, is it?" cutting in Marco but Sonic Interrupted with a smile on his face. "Don't worry, I'm only messing you, I can tell you didn't mean to, but seeing those Septarian lizards, I can see why." This gave Star and Marco a sigh of relief and then introduce their selves. "I'm Star Butterfly and this is my friend Marco Diaz and let me guess, your friends are "Tails" and "Knuckles" right?" she guesses because of the fox's twin tails and the echidna's spiked knuckle gloves.
"Actually, you're half right, my name is Miles Prower, but they called me "Tails" but you're right about Knuckles' name, how did you know" asked Tails curiously, which Star pointed at Tails' tails and Knuckles' gloves and said, "I just guess."
"Good guess" replied Tails.
"So, Star, Marco, why are those lizards attacked you?" asked Sonic, but before Star or Marco could answers they were interrupted.
"Well, it isn't Sonic, Tails, and Knuckles. I'm surprise to see you here" said Eggman in his Egg Mobile as he hovers over for our heroes to see.
" It's a flying Egghead" joked Sonic as here pointed at the Egg Mobile for everyone to see.
"Silence fools, I am Dr. Ivo Robotnik, the greatest genius in this or any world and I want your Chaos Emerald Sonic along with the Emerald she and her friend found too." The words shook Star and Marco and then Star said, "wait you're after the Chaos Emeralds?" which caught Tails attention and thought to himself about how Star knows about the Chaos Emeralds as Star realized and said, "which means those Septarian lizards are working for you?!"
"I don't have to explain my plans to you Star Butterfly, oh yes I know who you are, former princess of Mewni, give me your Chaos Emeralds or else."
"Or Else what?" asked Star getting ready to fight then Eggman replied "or else I'll take them from you by force." then Eggman push a bottom and suddenly small aircraft with a drill on each side on the front and equipped with a large rocket thruster on the rear, then Eggman move the Egg Mobile in front of it and shouted "Egg Hornet Go" then attach the mobile to the Egg Hornet.
"Egg Hornet, really Eggman, you already use that once before and I destroyed it, why use it again?" asked Sonic which Eggman replied as the Septarian Warriors they fought earlier regroup and back for round 2, "This time you annoying rodent, I got reinforcements."
Notes: Hello again, and again Star vs the Forces of Evil belong to Disney and Sonic belong to Sega, I don't nothing, also Blue Hills is a place I made up to set the scene for this story. again this is my very first fanfiction story, no one is perfect. Chapter 2 Egg Hornet Boss fight.