Undertale meets Shield

Betty's deal

Classic Sans sat against the wall of his new giant cell. He made so many attempts to get out, but no amount of blasters or blue attacks helped Sans in any way, it only made him more and more tired. He could only sigh and bang his head against the wall. After a moment of silence, Sans began to hum a tune as he looked up at the ceiling.

Let's go to the garden
You'll find something waiting
Right there where you left it
Lying upside down

As he kept singing this old song he hadn't heard in a while, he heard a thud. Sans thought nothing of it and shrugged his shoulders so he kept singing until he heard the thud again but closer. Sans stood up, walked into the middle of the cell and stayed silent, listening for whatever he hoped wasn't coming his way. It was silent for a moment, until he heard a giant crash behind him and was punched towards the wall he was facing with a groan. "What the heck?" He said as he stood up and looked at where he heard the giant crush. He heard grunting and saw it was the Hulk but his eyes were glowing pink. "Know why would you'd be he-" Sans said but froze as he began to glitch like crazy and saw an image of his soul being pierced by a pink needle of some kind. Then he saw Betty with her little friend, Kumu floating next to her. Each showing a creepy smile.

"Aw, is the little skeleton scared?" Someone said one Sans had stopped glitching. Sans began to gasp for air as he looked around for Betty and saw she was sitting on Hulk's shoulders with a smirk. "Hello little guy, I'm assuming you know who I am?" She said with a grin. Before Sans could answer, Hulk grabbed him and propelled to the top of the helicarrier where several guards and the Avengers stayed, all in battle positions. Fury also stood with the group but his gun in hand and a megaphone in the other. "Put the Skeleton down!" Fury ordered as he used the megaphone, Betty raised a brow in annoyance while Kumu hovered next to her. Then it seemed to have an idea and whispered something into her ear. She giggled at the thought and jumped down, the Hulk still holding Sans in one hand.

"How about we make a deal." Betty said, Fury held up his hand, telling the guards to wait and stay. The Avengers only listened because the Hulk could snap Sans in half. "I could let this sorry excuse of a Sans go, if you dusted every monster you have!" Betty said, Sans looked at Fury with dreadful eyes to not do it. Fury moved his glance to Sans and saw the skeleton shaking his head. "It's a deal." Fury said, Nat looked at him with a shocked and an angered look. Until she saw what he was doing with his hands behind his back.

Aim for her head

Nat narrowed her eyes at Betty who raised a brow with a smile. Then she laughed like a psychopath. Everyone gripped onto their weapons as they readied for the attack ahead of them. "I've been inside your head ever since you found out about those monsters! Do you really think I'm that stupid?!" She said and took a deep breath and glared at the group. "Turn him to dust." Betty said, the Hulk then began to crush Sans, causing him to yell in pain. Nat couldn't take it and sprinted to Betty. "Let him go!" She yelled and punched Betty in the face. Betty fell to the ground and laughed a little as she got up. Nat glared at Betty and suddenly a large blue glow appeared in front of Nat's chest.

"Integrity huh?" Betty said, Kumu formed her scythe and placed it in Betty's hand. "What irony." She whispered to herself, but suddenly, Nat's eyes glowed blue as she dashed to Betty and discs with sharp spikes on them appeared around her and then flung themselves to Betty. Her eyes went wide as she tried to use her scythe to deflect the attacks but Nat was so fast. Sans opened his eyes as Hulk stopped trying to crush him. "Kumu! Take care of the others for me!" She yelled to her little friend, it nodded and tried to hurt the avengers and was too fast for any of the guards to hit it. Sans looked over at Nat and saw the rage that filled her eyes as she tried to punch, kick and slice Betty. "S-shes going to get herself k-killed." Sans said and then began to think aloud. "Why? W-why help m-me after h-how I've t-treated y-you?" Sans asked himself, Betty kicked Nat down who flipped herself up and Sans saw how tired she was. Betty smirked as she kicked Nat in the stomach and was about to strike Nat in the head with the scythe. "NO!" Sans yelled in anger, something then zoomed to Betty and grabbed the blade of Betty scythe.

"Huh?" The two said, Betty looked at the figure and her eyes went wide with fear and shock. Nat looked at the figure and saw it was Ink!Sans. Ink balled his hand and delivered a blow to Betty's face to bad, it sent her to one of the rotters. "Thanks buddy." Nat said as she got up, but he didn't answer. "Ink? You okay buddy?" She asked and was about to touch his shoulder until a glitched out portal appeared in front of them put in the air. Error and Fresh Sans suddenly fell out from the portal but Error looked more afraid while Fresh just smiled like his normal self. "SQUID! Are you here!?" Error yelled, Nat was confused by the name. "I'm right here Error, no need to go crazy." Ink said in a calm matter. Error saw him and ran over to him with something in hand. Nat looked at it and saw it was Ink's viles.

"Are you nuts?! The last time you didn't have these you nearly destroyed an AU!" Error said and shoved the viles to Ink. Nat walked around Ink and saw that Ink's pupils were white circles.