Chapter One: Trouble Brewing

**Mushroom Kingdom - Isle Delfino - Beach**

"Happy birthday Peach," everyone there exclaimed, smiling. Peach, Mario, Daisy, Luigi, Toad and Yoshi were sitting at a large picnic table on the beach. There was a large floral pink cake on the table in front of them.

"Oh, thank you, everyone!" Peach responded. Mario started cutting the cake and handing out pieces. He just finished when all of the sudden there was a deafening cracking sound. Everyone jerked their head's up to see what happened.

The sky had a large purple … crack? That seemed to be the closest thing to it.

"What going on?" Luigi asked, fear edging his voice.

Suddenly, a circular purple thing appeared right near them. It seemed to be trying to pull something in.

**Ebott City (River)- The Bridge**

Everyone in the car was chatting. Juliska, who was driving, and Amity, who was in the passenger's seat, were talking about music. Undyne, Alphys and Frisk, who were in the very back were ranting about Anime. Sans was in the midst of telling jokes and pun while Papyrus was trying to get him to stop.

They were all content, until it happened. There was a large cracking sound.

"Oh my god!" Amity screamed. Juliska slammed on the brakes, but it was too late. The bridge was crumbling. The car pitched forward and fell.

"Seat belts off! Open the doors!" Juliska screamed as she did what she had said. She also quickly grabbed a small leather backpack that she always had with her and put it on.

"W-what?" Alphys frantically asked, but complied.

The car hit the water's surface and started sinking. Everyone starts to get out of the car, but Frisk. Frisk didn't move. She seemed to be staring off into the distance.

Undyne, not waiting for the teen, grabbed Frisk and pulled her out of the car. The car was completely under-water by the time everyone was out.

"What the hell happened?" Undyne shouted, treading water while holding Frisk.

"Look," Juliska quietly said, pointing the sky. There was a large purple crack in the sky.

"Let's just get to shore right now," Amity suggested, clearly fighting back tears.

"good idea kid," Sans replied. Everyone, one way or another, started making their way towards the shore. Undyne thankfully was a good enough swimmer to also bring Frisk to shore. Frisk still was unresponsive to anything and everything.

Once they were at shore Undyne put Frisk down. Alphys kneeled over her to see what was wrong. Juliska was cough and wheezing, and she sat down. She rummaged through her bag before she found her inhaler and used it.

"Frisk! W-what ha-happened?" Alphys asked.

"I had a … a flashback," she responded in a small voice.

"Oh," Undyne said, recognition in her eyes. "I'm so sorry about Frisk!"

"I-it's okay Undyne," Frisk said.

"A-alright. Is a-anyone hurt?" Alphys asked. Everyone said some form of no. No one was seriously injured at least.

"WHAT'S THAT?" Papyrus shouted, pointing to a circular purple thing. The grass' ends seemed to be pulled toward it.

**Green Hills Zone - The Hills**

"Sonic! Sonic!" Tails called out. Sonic stopped running on a dime, right in front of Tails.

"Yeah, buddy?"

"Sonic, there's something wrong! My monitor is picking up these strange occurrences, but I don't know what it is!" Tails frantically explained. "And a bunch of disappearances have been reported! I think it is connected."

"Woah Tails, I sure we'll figure it out!" Sonic reassured his friend. Just as he finished speaking, there was a loud cracking noise. Looking up, the two friends saw the sky a long purple crack it.

"Sonic! What's that?!" Tails asked, fearfully pointing to a circular purple thing. The grass ends were swaying toward it. Suddenly, it's suction became greater and started pulling the two toward it.

"Sonic!" Tails screamed, getting sucked into the circular, now discovered to be, portal. The portal sucked up Sonic as well just a few seconds after. Once the two friends had been caught up in the portal, it disappeared completely.

Hey guys, so I was planning on putting this out later, but I didn't have anything to post this Wednesday, we here we are. And what would one of my Undertale fanfictions be without an Amity? I don't know if this will even happen, and the title may change. Though this is in the Mario×Sonic section, Undertale is equal to the others in how central it is to the story. I have some questions for some stuff I am unsure of;

Should this be an only video game crossover, or just a bunch of different things?

Should the characters of all three main groups mix, or should one stay solitary for a little.

Are there any other franchises that you think should be in this? (Not guaranteed to happen)

Well, have a great day!