A/N: Today's prompt for Captain Hill Week is "cross-over." I decided I'd continue a theme I started back in "I Don't Dance" chapter 14 "No Ordinary Kids." So, yeah, Ben 10 cross-over. Special and billions of thanks to two of my sons for their help. Mainly to "Clint" who brainstormed with me to come up with this idea, then proof-read the first draft and made it a million times better. But also to "Bruce" who helped me pick the alien for this chapter and the alien tech for the story. (Yes, I did "name" my kids after various Avengers. ;))

This story is, obviously, A/U. It takes place within my A/U, as well. It's three years after Hope was born so no PTSD-Steve and no missing-and-presumed-dead Maria. hehe. The Ben 10 characters in this particular story are based on Ben 10: Alien Force, so Kevin is a good guy. Title is from the song prompt for today (by ZZ Ward).

(More notes at the bottom.)

Please R&R.

The elevator doors in the Avengers Tower slid open for Ben, Gwen, and Kevin to reveal Tony Stark waiting for them.

"Ben! Gwen! Good to see you, kids," Mr. Stark put out his hand and shook theirs as they stepped off the lift.

"Mr. Stark," Gwen said. "This is Kevin Levin."

Stark took Kevin's hand in greeting and lead them into the Avengers common room. It had been remodeled since the last time Ben and Gwen had visited a few years earlier, but that didn't surprise Ben. It had been different every time they'd visited. Gwen thought Mr. Stark grew bored and needed change frequently.

"Sit down, sit down, let me get you a drink," Mr. Stark said as he walked around the bar.

"I'll take a beer," Kevin said, smirking.

Stark raised an eyebrow and gave Kevin an incredulous look. Then he reached under the bar and pulled a bottle out and handed it to Kevin. Ben glanced over and read the label, "Rootbeer." He chuckled at Kevin's expense.

"Cap and Maria will be down in a minute or two," Mr. Stark told them as he poured their drinks. "They had to get Hope down for her nap."

"Oh, I wanted to see her," Gwen said.

"I'm sure you'll run across her sometime in the next few days. But we haven't really said anything to the kids about you guys visiting, just in case something happened, you know, and you couldn't make it."

He came around the bar and handed Ben and Gwen their drinks before he rested in a chair across from the sofa where the three friends were seated.

"Thanks, Mr. Stark," Ben said.

"Ben, you are all over 16 now, and have saved the world a few times over, I think we can drop the formalities," Stark told them. "Just Tony, OK?"

Ben and Gwen nodded.

"Besides, now that I've got a kid I have more people calling me Mr. than I ever wanted: Teachers, doctors, other parents. It makes me feel old," he said and smiled at them.

"So, you have something since I saw you last," Tony said, and pointed at the Omnitrix on Ben's wrist.

"Yeah, there was an incident," Ben said.

"I've heard," Tony said before Ben had to rehash the story of how he came to be wearing the "watch" again after all these years.

A bell sounded briefly to announce the arrival of the lift and Captain America and, his wife, Maria Hill stepped out as the doors opened.

Gwen stood first and quickly walked over to greet them both with hugs. After all the greetings and the refusals of formalities, "Just Steve, Just Maria," were finished, they returned to their seats as Steve got drinks for Maria and himself.

They talked for a while as they caught up on events since the last time they'd been together, and the three adults and Kevin got a feel for each other. Kevin had, as usual, been nervous about visiting with The Avengers. His past criminal activities made him feel he wouldn't cut it with people like this, but things were going smoothly and Ben could tell that the four of them were going to get along just fine during the visit.

About an hour into their visit, JARVIS interrupted their conversation.

"Sir, someone is attempting to send a message to you," he said.

"Who is it, JARVIS?" Tony asked.

"He will not say and he has overridden my system," the AI replied.

There was an immediate shift in the room and all six were on alert.

"Show it," Tony told JARVIS.

An image emerged on a screen on the wall behind Tony as he turned to face it.

"Mr. Stark," a gravelly voice Ben knew all too well spoke. "You have something I require."

"Vilgax," Ben, Gwen, and Kevin said in unison.

The three adults turned to them.

"You know this, um, person?" Steve asked.

"Ben Tennyson," Vilgax' voice was smug. "Today truly is a day that will live in infamy, for you."

The screen went blank and before the six could do so much as discuss the implications of the call, the glass wall to the veranda outside the common room exploded in on them throwing the group across the room.

Ben wasted no time. His hand flew to his wrist and he twisted the control of the Omnitrix to the alien he wanted. He slammed his palm against the three dimensional representation. Instantly, Ben felt his blood begin to churn as his body stretched and grew.

"Humongousaur."

He looked out the doors to see two of Vilgax' drones firing into the room. To his left, Gwen was firing mana* while Tony, who already had his Ironman suit on, was flying out to battle them in the air. On his right, it looked like Kevin had found some form of metal to transform himself. Ben didn't have time to wonder why his friend was red. Kevin headed to the veranda with Steve was ahead of him, using his shield to cover Maria as she fired on the drones. But, shortly, three more drones joined the other two.

"Maria, go to Hope," Ben heard Steve yell.

She looked as if she might argue for a moment before she nodded resolutely and Steve covered her as she ran back into the room and toward the emergency stairs.

Ben turned his attention fully to the drones now as he stepped onto the veranda. Steve was using his shield to deflect the blasts from one drone and redirect them to the one next to it. Kevin hollered to Gwen to use her mana to lift him up to the top of one of the ships and Gwen ran over to him. Ironman was engaged with two of the ships and they were distracted. Ben reached up and grabbed one, smashing a huge fist into the engine and pulling out the components, disabling it. He dropped it and Tony coaxed the other ship closer to Ben, who grabbed it, then turned quickly. Gwen and Kevin had almost destroyed the drone they had attacked and Ben watched as the drone Captain America had used his shield against started to smoke before it exploded. He turned with the drone he had in his hands and slammed it into the remaining drone, causing both to explode on impact, which blasted Ben and Steve back into the common room.

Ben looked to make sure Kevin and Gwen were back on solid ground before he transformed back into himself.

"What was that?" Tony asked as he settled back down onto the floor of the common room.

"That was Vilgax," Gwen said

"He wants Ben's Omnitrix," Kevin added.

"But why did he leave without it?" Steve asked.

"Yeah, that wasn't much of a fight compared to what we normally experience," Gwen said as she turned to Ben.

He only shook his head and shrugged. He was as perplexed as she and Kevin.

"JARVIS, are you back online?" Tony called into the air.

"Yes, sir," the AI replied.

"Are we secure?"

"Yes, sir."

"What about the other people in the building?" Steve asked. "Are there any injuries?"

"No, Captain. The attack was centered in this room and, at this point, there are no injuries to report."

"Well, thank goodness it's Saturday so there weren't a lot of people around," Tony said.

"Let Pepper and Maria know everything's OK up here now, but they shouldn't bring the kids," he told JARVIS.

"Yes, sir."

"What exactly is the damage?" Ben asked.

"JARVIS?" Tony cued the AI to answer Ben.

"Sir, most is contained to this floor with minor damage in surrounding areas, including the roof of the 30th floor where several of the ships crashed."

"I need to alien proof this building," Tony mumbled.

"And your Mark 1000 suit was taken during the battle as well, sir," The AI finished.

"What?" Tony asked, and Ben thought the man might have paled.

"The Mark 1000 suit."

"Yeah, I heard you."

Tony groaned.

"What suit is that?" Steve asked.

The billionaire rubbed his hands over his face in frustration.

"It has an alien tech core, it's just in development but the core is powered by something called 'sub-energy.'."

Both Ben and Gwen gasped at the mention of the Sub Energy.

"I have a bad feeling Vilgax wasn't really after Ben this time," Kevin said.

A/N: So, this is obviously a multi-chapter story, which, I must confess, will not be finished until after NaNoWriMo. Both "Clint" and I are writing for it this year and we won't have time to work on it.