A crowd has gathered around a giant screen to see the President deliver his speech. Danny and Hikaru are in the crowd.

"My fellow citizens, the assault against the headquarters of Dr. Eggman has begun. Our military forces will press on until Eggman is no longer a threat to the world. We will not fail. Dr. Eggman must be stopped now!" President said.

"Whoa... This'll be a heavy-duty fight." Danny said.

"I hope Y/N and Sonic are okay." Hikaru said.

At the vicinity of Eggman's base, a hail of missiles is launched at the incoming wave of fighter jets. Knuckles is hiding inside one of the jets. As the missile is launched, Knuckles rides it toward the fortress, leaping off of it and clinging to the outside of the fortress right before the missile explodes. He then begins to scale the building.

Inside Eggman's base, Y/N, Rouge, Topaz, and their troop proceed through the fortress until Rouge stops them.

"Hold it."

"Why did we stop?" Topaz asked.

"Because we're about to get a visit from Eggman's welcome wagon."

As if on cue, an E-12 Behemoth approaches them.

"I'll take it!"

Rouge flies toward the Behemoth.

"That's my line!"

Y/N brought out her giant fist whip and jumped after her.

"Rouge! Y/N!"

Rouge dodges a punch from the Behemoth, then leaps to the other side, and dodges another punch. Y/N spun the giant fist and swung it at the robot's head, knocking them backward.

"Hurry! Set the charge!" Rouge ordered.

Topaz attaches an explosive device to the Behemoth.

"Okay!"

Rouge gives a wink and her and Y/N gave her a thumbs-up before Topaz presses the button. The device explodes, causing the Behemoth to fall through the floor. Topaz, Y/N, and Rouge high-five and they ran down the hall and arrived at a door.

"There!"

Suddenly, a Behemoth breaks through the wall behind them.

"There's another one?!"

"Don't sweat it, sweetie. Y/N and I'll handle this robot. You lead the team to the generator room and set the charges."

"Alright, guys, follow me!" Topaz nodded.

Y/N and Rouge take on the Behemoth as Topaz leads the troops toward the power station. But a platform full of Guardbots rises up from the floor in front of them. Rouge and Y/N are struggling with the Behemoth.

"Missed me, slowbot!"

The Behemoth suddenly grabs her.

"Rouge!" Y/N shouted.

Rouge becomes steamed, then delivers a powerful kick to the robot, sending it reeling. They then saw Topaz and her officers ducking under the Guardbots' laser fire. Suddenly, Knuckles breaks through the wall.

"Knuckles!" Rouge and Y/N shouted.

Y/N quickly hid her giant fist whip behind her back and you could see under her helmet she's sweating, feeling nervous. But at the same time, her helmet did help keep her identity safe, so there's no way he'll recognize her. Knuckles punches through the Guardbots, destroying them.

"Wow, thank you. You're one of Sonic's and Y/N's friends, aren't you?" Topaz said with a grateful smile.

"We're not friends! At least not me and Sonic." Knuckles said.

"So he claims.." Y/N sweatdropped.

Rouge quickly hid her wings.

"But you do know him, don't you?"

"Maybe. By the way, what are you and your crew trying to do here anyway?"

"We came here to destroy Eggman's base. In fact, we're on our way to sabotage the generator room right now." Rouge replied.

"There's no way you can do it. That room will be impossible to get into." Knuckles crossed his arms.

"Really?" Rouge asked.

"We have to try!" Topaz exclaimed.

"You'll fail... unless you have me along. I can't wait to see the look on Sonic's face when he finds out that I helped to defeat Dr. Eggman while he missed out on the glory. That'll mess with his ego."

"Is he bragging about it or is he still competiting my brother because I swear...?" Y/N thought with a quiet sigh.

"Sounds like you have an inferiority complex."

This made Y/N giggle as her body shook, luckily it was muffled thanks to her helmet.

"I... have a... what?"

"Oh, nothing. Never mind, Knuckles." Rouge said with a smirk behind her mask.

"Ok... By the way, who's that?" he asked, pointing at Y/N, not knowing it's her, making her smile in relief.

"Oh, that's just my assisstant. This person is just a quiet one." Rouge said.

"I am not your assistant." Y/N thought with a tickmark. "But thank you for the cover."

"Huh? What're you talking about? She's our helper and her name is Y/N." Topaz said with a innocent look.

"Darn..!"

"Y/N?! I thought I almost recognized you since you're holding the whip behind your back that I clearly remember that weapon belongs to Y/N." Knuckles said.

Y/N slumped that her cover was blown.

"Whelp, that went well." Rouge shrugged.

Y/N put her whip away and took off her shade from the helmet for Knuckles to see her F/C eyes and her nose.

"Alright, you caught me.."

"What are you doing here? Does Sonic know you're here?"

"No. I just want to do this mission on my own. Plus, he thinks I'm visiting Hikaru right now."

"You do realize if he find out, it won't end well between you two. Remember what happen last time?"

"Don't remind me.." Y/N sighed. "But please don't tell Sonic about this, Knuckles. I can do this."

Knuckles sighed, knowing she won't back down when it comes to mission.

"Alright. But if he finds out, let's just hope he understands. If he doesn't, you're more than welcome to come visit me anytime for some comfort."

"Knuckles.."

"I hope you two are done with your love quarrel, we still have job to do." Rouge went between Knuckles and Y/N, slightly glaring at Knuckles unnoticed.

They nodded and they made their way to the generator room and set up the bombs.

"The demolition charges are all set, ma'am." GUN soldier said.

"Good work. Well, looks like we're ready, Rouge." Topaz turned to Rouge only to find her gone "...Hey, where did Rouge go?"

Y/N and Knuckles pointed up.

"I saw her go that way." he said.

"What in the world is she doing there?"

"And I bet she's going after the Chaos Emeralds as always.." Y/N said.

Meanwhile, Rouge is on a platform above them.

"Aw... Eggman must be keeping the Chaos Emerald someplace else now."

"Hey, Rouge!" Topaz called.

"Yeah?"

"Get down here! We've gotta go!"

"Go on; I'll catch up."

"We need you!!"

"There's something I've gotta take care of first!"

But then the door shuts in front of Rouge.

"Uh-Oh. Not good."

Topaz, Y/N, Knuckles, and the soldiers climb up to Rouge's level.

"Hey! What are you up to, Rouge?!" Topaz yelled.

"They locked us in, but not for long."

She attempts to kick the door. A few kicks later, she is winded.

"I can't kick through..."

"Leave it to me!"

Knuckles marches up to the door and lands a heavy punch on it. He sweatdrops when he sees no damage has been done.

"Huh? I didn't even make a dent."

He throws a volley punches at the door, but only manages to dent it.

"How can Eggman make a thick door that it's hard to break down?" Y/N said and brought out her giant fist whip and swung it at the door, only leaving a big dent.

"It's strong."

Y/N kept on swinging her fist whip at the door and soon got tired after she only made a few more big dents. The bomb timer shows less than ten minutes left. Y/N then took out her katana and made an attempt to slice the door, but it only left a scratch on it. She grew frustrated as she tried to think of a way while Rouge and Knuckles used teamwork and attack the door together. Her idea popped out and she took out the crystal from her backpack and stare at it as it started to glow. She noticed the crystal brought out a bright glowing smoke towards her katana, powering it as the blade glows white. Y/N then realized what it's doing and hid her crystal back in her bag.

"Rouge. Knuckles. Stop what you're doing right now." she called.

Rouge and Knuckles stopped their attack and turned to her only to face her white glowing katana she held in her hand. Topaz and the soldiers saw it too.

"Stand back."

They then did what she's told as Y/N strodded over to the door. She then swung her katana once again and sliced the door. The door fell into pieces after the power of the crystal destroyed it. Everyone looked at her in shock. The white glow of the katana faded away from the blade. Y/N sheathed her katan and looked at the group.

"What?"

"How... did you do that?"

"That's a secret I rather keep. Let's go before the bomb blows up!"

Everyone nodded and ran down the hall as they went to the one hall, but someone else went the opposite. Y/N had ran down another hall, making Knuckles, Rouge, Topaz, and the Special Forces Team to stop to see her.

"Wait, Y/N! Where are you going?!" Knuckles called.

"Gotta deal with that egghead and I'm sure my brother is here and would need some help! Just go!" Y/N yelled, taking off her cat helmet and turned them small, placing it in her backpack, and kept on running.

"Y/N!!!" Knuckles and Rouge called, but she was gone.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sonic and Eggman were battling when Eggman got a call and he answered it.

"Hello?"

"Sorry to bother you, Doctor, but we have a problem. A group of intruders is locked in the generator room. We are unable to determine whose side they are on." Decoe said through the phone.

"Huh?"

Eggman activates the Eggmobile's screen, which shows Knuckles, Rouge, Topaz, and others are running down the hall and Y/N running down another hall.

"Knuckles?! Y/N?! Those are our enemies, you dumb-bot!"

"Then we will eliminate them."

"Y/N?! But I thought she's visiting Hikaru like Ella said! Oh, she's so gonna get it once we're done here!!" Sonic growled in his mind.

"What are they doing in the generator room anyway?"

"I am not certain, but they did mention something about demolition charges."

"They whaaat?!"

Just then, the door were smashed through and they reveal Y/N with a powered giant fist whip from the crystal before the glow disappeared as soon as she smashed the door. Y/N looked to see Sonic glaring at her, making her chuckle nervously.

"We'll talk about this later, for now. Ready for this, sis?"

"As ready as I'll ever be."

"Y/N! I would have known you would come by now. But this ends here! Guerra-Hard! Get them!"

The hedgehog siblings sped towards the robot.

"Run and skate all you want. Guerra-Hard will still pulverize you both!"

Guerra-Hard tries to stomp on Sonic and Y/N, but they leap back, then they run and skate up the leg.

"Get them!"

They then broke through Guerra-Hard's torso, and Sonic grabbed the Chaos Emeralds. Y/N held onto his waist as they passed through the other side. She could feel the emerald's power flowing through her, even though she's only holding onto him, it must have been their close bond.

"Gah! Stop them!"

"Yeah!" Sonic cheered.

"Whoooooo!!" Y/N cheered.

Sonic harnesses the power of the Chaos Emeralds along with Y/N and she slowly let go to find herself flying along with him, making him smirk, and they fly through Guerra-Hard.

"No! Bring them back!"

Eggman screams as Sonic and Y/N fly through Guerra-Hard repeatedly before crashing through the wall and leaving the fortress - leaving a sparking Guerra-Hard behind.

"Oh nooo!"

Eggman ejects and flies the Eggmobile to safety moments before Guerra-Hard glows and explodes violently. The explosion has severely damaged the fortress. Sonic and Y/N flew through the fortress twice, damaging it further. They then zoomed through the base and passed through Knuckles and Rouge in a hallway.

"Hi, Knuckles and Rouge! Bye, Knuckles and Rouge!!" Y/N shouted.

The bomb detonates, completely destroying the fortress. A large burst of light engulfs the entire island before the fortress disintegrates into the sand. Everyone safely watches this from the beach.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Back at Station Square, the crowd erupts in cheers upon seeing the fortress being destroyed.

"Wh... Where's Sonic and Y/N?" Danny worriedly asked.

"Yeah. Do you think he made it out of there okay?" Elmer said.

Hikaru bit his lip.

As for Chuck, Cream, and Cheese at the mansion, they're also worried for Sonic and Y/N.

"That fireball's huge. I hope Sonic and Y/N weren't still in there..."

"I bet we'll see them any second." Cream turned to Cheese. "Right, Cheese?"

"Chaaaoo!" Cheese replied.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Suddenly, Sonic and Y/N burst out of the smoke. Their Chaos Emerald flight power wears off, and they landed on the nose of the X-Tornado. Sonic gave Y/N the cyran Chaos Emerald and they both held one in the air, claiming their victory.

"Yeah!!" they cheered.

"Sonic!! Y/N!!" Tails, Amy, Chris, and Frances exclaimed in happiness.

Danny, Elmer, and Hikaru who are watching this from the big screen were relieved and happy as the crowd went wild.

"Way to go, Sonic, Y/N!" Danny cheered.

"Who's that girl with Sonic?" someone asked.

"That's Y/N! Y/N the Hedehog and she's Sonic's sister!!" Hikaru said.

"Sonic's sister?"

"Yep!"

The whole city cheered for their new heroes.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

They're now back at the mansion after they added two Chaos Emeralds to their collection. Y/N thought she was going to rest to her own room when Sonic stopped her.

"Don't think I forget about you and your so called 'visiting Hikaru'." he glared.

Y/N chuckled nervously and started sweating.

"Why did you lie to me? You could have told me."

"Well, I know you wouldn't be interested in joining them because you rather go solo. I also wanted to because I wanted to protect my friends and I know I can do this on my own without shiny armor coming for my damsel in distress. You know that I can handle myself, and yes, I should have told you sooner without you worrying me." Y/N looked down.

"That's true and I know that. But I can't promise you about me worrying about you. I don't like you lying to me and I have every right to know where you are." he said and patted her head. "I may be overprotective, but I'm saying this because I love you and I don't want to loose my sister."

"I know." she sighed and hugged him and he hugged back.

"Promise me that you'll always tell me where you're going, okay? No more secrets."

"No more secrets. And I don't want to loose you either and I love you too."

Sonic and Y/N then wrapped their pinky fingers together and smiled at each other.

"Night, Y/N. Have a sweet dream."

"Night, bro."

They then parted their ways to get some sleep.

"Oh, and one more thing!" Sonic said.

Y/N stopped and look back at him.

"Hm?"

"If you ever meet the boys, don't go near them. Let me know if they're good or nothing but trouble." he said with a smirk and walked away.

"Wait, wait, wait! What does that mean, Sonic? What do you mean by that? Who are you talking about?"

Sonic just chuckle and kept on walking as he's going to keep an eye on those certain boys that ever goes near his sister.

"Sonic!! Hey! Are you listening?? Hey! Sonic!!!"

https://youtu.be/Wr0a1yfNi0s