Note: Star vs the Forces of Evil belong to Disney and Sonic the Hedgehog belong to Sega, I do not own anything, I know this story sound weird, but believe me I'm trying my best, no one is perfect it is hard to write a Star/Sonic crossover fan story, please understand. but there will be some lore after the fight with Egg Hornet and Janna is in this chapter. Let's continue the story where we left off, also once again, this is my very first fanfiction.

Sonic and Star in Adventure in Mewni

Chapter 2 - Egg Hornet Shenanigans

Suddenly out of nowhere a small rock hit the windshield on the Egg Mobile which startled Eggman and left a crack in it, after a few seconds, Eggman yelled out in an angry voice, "WHO DID THIS?!" Eggman lean toward the front of the mobile and look around and saw Star holding a small rock in her hand which Sonic and his friends, Marco and even the Septarian Warriors stare at her with surprise look on their face.

"Eggman is it? I don't you to talk about your plan, you team up with the Septarian lizards to locate these Chaos Emeralds to take over the world and/or make life miserable for us or whatever, I been through this before with 3 other villains I met a few times before so if I were you I would give up and go home now." said Star with a confident look on her face. Then Tails spoke up to Star in an attempt to reason with her "Star, I know we just met, but Eggman is not to be mess with, he's a lot smarter than he looks."

"Oh Tails, believe or not I dealt with people like this cracked egg before, I can deal with this." then Marco cut in. "But Star, this guy is flying in an aircraft?" then finally Eggman yelled "Enough of this gibberish and as for you, you pipsqueak of a former princess, you will pay for my windshield, Septarian Warriors ATTACK!" and immediately the Septarian Warriors charge at our heroes as Eggman fired air-to-surface missiles as he active the Hornet's drills which began to rapidly spin around.

"Missiles, he got missiles?!" yelled Marco as Sonic using his super speed to grab both Star and Marco and move them, along with himself out of the way and avoided the missiles as the rockets exploded hitting the ground.

"I admire your confidence Star but it's best you let me handle Eggman, me and my friends dealt with Eggman before back on my world."

"Your world?" said Marco as he realized that Sonic and his friends are not from New Mewni, "you guys and even Eggman are from another world?"

"I'll explain after I deal with Eggman" answered Sonic, unaware that a Septarian sneaking up behind him. But Star noticed and rush in and punch the lizard before he got a chance to use his spear on the Hedgehog. "Hey thanks" said Sonic but then Star rush to face two more Septarian Warriors and spin kick them out of the way.

"Sonic, I know you're protecting us, but we can handle ourselves, plus something tells me that, you going to need our help since you're new here."

Marco does have a point. He and his friends don't know anything about this new world they're in and it's seemed that Star and Marco have indeed does this before and know a lot of New Mewni.

"Ok Diaz, I can trust you and Star, but steer clear from the Egg Hornet and it's missile."

"LOOK OUT" yelled Marco as he grabs and move Sonic and himself out of the way just in time to avoid getting crushed by the Egg Hornet as it rams it drills into the ground which give a clear open for Sonic to use a spin jump to hit the Egg Mobile once before the Egg Hornet up itself out of the ground and back in the air.

"Fair warning, the Egg Hornet also do that, actually it a basic pattern of missiles and ramming into the ground and repeat."

"Ok" agreed Marco and he and Sonic ran in to join the fight.

Meanwhile back in Neo Scrap Brain Zone, in the Zone's central command room. Seth watches the battle between Egg Hornet and our heroes on a giant computer screen, studying his enemies' moves, abilities, even powers. But he most watch Star as he witnesses 3 more of his Septarian Warriors knock out with ease. This made him concern, but then one of Eggman's robots walk up to him and said "Lord Seth, our joint Septarian/Badnik squad lead by Rasticore has successfully taken over Monster Temple, sir."

"And the Chaos Emerald?" hiss Seth.

"We managed to get the Emerald from the former king and queen of Mewni, River and Moon Butterfly sir, they been place in the capsules with the rest of the Temple's staff in the Grand Hall as prisoners and so the takeover still remain a secret from the rest of the resident of Echo Creek for now."

"Good, good, you're dismiss for now and report this to Eggman when he returns."

As the robot walk away back to his post, Seth continues to stare at the screen and whispered to himself. "Too bad Eclipsa, Globgor and her hybrid baby are out of town for political business, but it's a good opportunity to set a trap for them when they return. Oh, if only Toffee was still alive, before that butterfly got rid of him." as he stares at Star on the screen with a menacing look on his face.

Back at Blue Hill, all of the Septarian Warriors are defeat and sonic with a helping hand from Tails by using his tails to fly Sonic up in the air, make that final blow on the Egg Hornet and began to cause a chain of small explosions before the Egg Hornet itself exploded leave Eggman in his Egg Mobile to slowly crash onto the ground, apparently defeated.

"Well, that wasn't so hard." said Star as Tails put out his red Chaos Emerald from his M.E.D.E.L device but suddenly, catching everyone off guard, Eggman push a bottom and a metal extension claw shot out from the side of his mobile and grab the Emerald then raise the Egg Mobile back up in the air as Tails shouted "No the Chaos Emerald."

"Hahaha, now I got two Emeralds for my collection and for my latest plan" laugh Eggman victoriously as he quickly threw a smoke bomb to the ground and use the black smoke cloud give him a chance to get away as our heroes try to clear out the smoke.

As the smoke cleared, Eggman was nowhere in sight. "Hey, he got away with our Emerald." said Star as she and Marce face Sonic and his friends.

"That's not the worse part, he said he now have two Chaos Emeralds, which means Eggman already have a Chaos Emerald with him along." explain Tails. Then Sonic said to his best friend "don't worry Tails, we can get it back" then urn to Star and said "ok with that's out of the way, I guess there's a lot of explaining to do. but before that, I like to ask, how did you know about the Chaos Emerald?"

Star put out the white Chaos Emerald out from her star shaped bag and show it to Sonic and his friends.

"A Chaos Emerald, you have one with you the whole time, I guess that explains why Eggman and those Septarian lizards attacked."

"Yeah, you see our friend Janna gave us a makeshift homing tracker to find these Emerald" explain Marco, "there are rumors going around that these Emeralds has magical powers and those Septarian we face are part of a rogue army who are cause us trouble recently and they are looking for these Emeralds believing they can use it to cause more damage. Now it's your turn, how do you know about these Emeralds, and about that Eggman guy?"

Tails began to Explain, "well, you two, first We come from the Planet Mobius, which is not obvious by now, we are not from your world, and so are the 7 Chaos Emeralds, they come from our home, the Chaos Emeralds does indeed have a mysterious, mystical, and scientifical powers which turn thoughts into power."

"So, these Emeralds do have powers?"

"Yep, but there is a giant emerald called the Master Emerald, which our friend Knuckles is the guardian of, control all 7 Chaos Emeralds at once, just recently Dr. Ivo Robotnik, a.k.a Dr. Eggman, a villain from our world who try to take over Mobius with his robot army and who we stop his evil plans many times before, at once point somehow make contact with your Septarian using his Chaos Emerald and learn about the 5 remaining Chaos Emeralds here on your world, so they must have team up and just a few hours ago back in our world, steal the Master Emerald and brought it to your world so we came to here with the help of my new invention, and the rest you already know."

The part about Eggman making contact with the Septarian is just Tails' theory. He doesn't know how and when Eggman came cross New Mewni and the Septarian, since they know only little about the Septarian and their goals and their leader, other than learning that the Septarian are from New Mewni. But he feels like Star and Marco could know since they seem to know about the Septarian.

"Wow, that's a lot to take in," began Star with a worried look on their face. "You guys should know that my world, New Mewni is a fusion of two worlds, Mewni, my world and Marco's world, Earth and it was the result of me destroying Mewni's Realm of Magic." this gave Sonic, Tails, and Knuckles a confused look and then Tails asked, "what do you mean by that?"

"Look it's a long story, but it's better we can tell you as we head back towards Echo Creek to our friend's house, our bikes are not too far from here, besides, in a way, we share the same goal of stopping our enemies from using the Emeralds to do evil things in fact that's why we're here." said Star. A few seconds of silence as Sonic, Tails, and Knuckles look at each other with unsure looks on their faces but they know that Star and Marco earn their trust. Finally Sonic with a smile on his face spoke "sure Star, I guess we can tag along, you did help us."

"Oh, that's great, we can tell you about us and our world and you can tell us about yourselves and about your world and how you got here without magic." said a very excited Star and then she handed her Emerald over to Tails knowing that she could trust her new mobian friends. "Here, you can have this, I can tell you can be trusted with this, after all, these Emeralds are from Mobius, from your world, so it's fair to give this back to you."

"Well, thank you Star" then Marco's phone began to ring, and he pick up to hear a voice that is way too familiar to Marco.

"Hey Diaz, did you find it yet?" said the voice through the phone.

"Yes Janna, we did and you're right, these Emeralds are from another world, and it's turn out there are 7 of them, not 5." Answered Marco. Tails turned to Star and asked her while Marco talks on the world "Oh this Janna, is she the friend you mentioned, the one who built your, makeshift tracker?"

"Oh yes, Janna has an interest in paranormal stuff which is how she found out about the Emerald's powers and you along with Janna's weeks of research confirmed it." then Star put out a modified two-way handheld radio repurpose into the tracker Star mentioned earlier. "Wow, I'm impress" said Tails as he examines the makeshift device. Then Marco walks up to Star and let Janna know that they are bring Sonic and his friends to meet her at.

"Ok, we need to get going, Janna is expecting us at her home, ready to go?"
"You bet we are."
"Great, now let me explain how New Mewni became as it is 3 weeks ago, you see a long time along in a faraway magical land called Mewni, live a princess named Star Butterfly." Star began to tell her story, how she used to be a princess with magic, how she met Marco and about her own adventures to Sonic and his friends, so they walk towards Star's and Marco's bikes so they can get to Echo Creek faster.

Note: Star vs the Forces of Evil belong to Disney and Sonic belong to Sega, I don't own anything and again this is my very first fanfiction story, my story may not be perfect. In fact, no one in perfect. I'll improve as I continue to write this fan story. In the next Chapter, as Sonic and his friends learned about Star's history and about New Mewni. Our heroes will arrive at Janna's house to come up with a plan and when they learn that the Monster Temple has been taken over.