Set during the Avengers
Loki was being held in the most high-tech, most secure cage SHIELD had to offer.
But Fury knew he was planning something. There was no telling what, but the god would not sit idle forever. Fury glared at the security monitor showing the hastily assembled team of powerhouses known as the Avengers. They weren't taking this seriously, refusing to work together like petty children.
"That guy's brain is a bag full of cats." Banner remarked. "I can smell crazy on him."
"Actually," Thor boomed, sounding nostalgic. "My brother prefers canines."
The rest of the team blinked at him.
"Thor, that wasn't what I meant- -" Banner started.
"We should stay focused on the task at hand- -" Rogers said at the same time.
AWOOOO!
What sounded like an enraged wolf howl, but about twenty times louder than the average wolf howl, cut off whatever they were going to say next. It came from the direction of Loki's cage.
The director was not amused. They were forty thousand feet high. Wolves could not sneak on board. So naturally, the culprits were either a bored Iron Man, or their special prisoner.
Fury pulled out his guns and headed to the prison, cursing up a blue streak. If this was Stark's idea of a joke, he would kill the billionaire.
The Avengers were already on guard. Steve had pulled on his mask and held his shield in front of him. Tony was already decked out in Iron Man gear. Natasha's guns were cocked and ready. Bruce did not have any weapons, but he was ready to Hulk out if he had to.
Thor seemed to be the only one who was unconcerned. In fact, he was grinning from ear to ear as he rushed to meet whatever had made that howl.
Agents, Avengers, and Fury stopped dead at the sight before them.
Loki was lying on the ground, looking somewhere between fond and exasperated.
Lying on top of him was a giant mass of fur, filling up the entire cage.
"What the actual hell?" Fury exclaimed.
"That is a giant wolf." Steve said blankly.
Natasha stared impassively, but she was cooing inside. It was cute! She wondered if she could keep it as a pet...
"Prisoners of state are not allowed pets!" Maria Hill yelled.
Loki looked offended. "Fenrir is not a mere pet."
The wolf, nearly ten times the sorcerer's size, had him pinned down and was licking his face happily, letting out joyful doggie barks.
"Fenrir!" Thor boomed, dropping Mjolnir and rushing to the cage. Fenrir howled excitedly and bounded over to the glass, staring down at the asgardian.
"I have missed you, nephew! How did you come to be here?"
"He was worried for his father." Loki answered amusedly, not making any effort to get up. "My son thought I was dead, you see."
"Wait, wait, wait." Tony said, cutting through Thor's exclamation of 'We all thought you were dead!'. "This giant-ass wolf...is your son."
"Yes."
"You...fathered a giant-ass wolf."
"Fathered and birthed," the trickster agreed.
Tony stared. And stared some more. Next to him, Bruce felt his brain break.
"Brother, you did not call Fenrir here?" Thor inquired.
Just then, there was an explosion that rocked the Helicarrier.
"No." Loki said, looking thoughtful. "But I suppose extra help would not hurt. It seems like the Hawk has finally arrived. Fenrir, get me out of here and eat everyone."
Because Loki would totally do that.
And about Fenrir, Loki got impregnated after eating his lover's burned heart.
RnR!