It kinda starts a bit far into the story, but that's because I couldn't come up with a way for them to get into the carrier. But in a nutshell Banner and Loki are captured and taken aboard on a giant plane.
...
Loki tried to punch the man in front of him but the guard shoved him up against the wall, his hand enveloping Loki's throat. He and the human named Banner had agreed to work together to get out, so where was he? Loki heard a loud noise not to far away from where he was pinned, if that was the Hulk everyone on the carrier was doomed, even Loki. The man started to punch Loki, making Loki's vision become blurry. Suddenly the man stopped, there was a loud yell that Loki knew came from Hulk, and the hand holding Loki's throat was gone.
Loki found himself falling to the ground and coughing loudly from lack of air. He tried to see what was going on but just couldn't seem to focus. He heard a loud of pounding and then some gunshots. Suddenly the man screamed, but than it instantly stopped. Loki stood up and leaned back against the wall, trying to keep his balance. He blinked the blobs in his vision away to see the Hulk staring right at him. The memory of Hulk pounding him into the ground filled Loki's mind and he backed up against the wall.
Gunshots sounded and bullets landed on the Hulk's green body and he ran towards them. Loki quickly picked up the dead human's gun and followed Hulk down the hallway. Loki jumped the last two steps and looked around the hanger. Hulk was throwing men around and pounding the others into the ground. Loki couldn't help but smile, it was amusing to see the humans in pain, or at least dead. Loki took the liberty to shoot one that was climbing on Hulk's back. Hulk looked over at him as he shoot a few others. Loki opened the hatch and looked over at Hulk, who looked back.
"Let's take our leave," Loki said. Hulk threw the men off him and jumped out of the hatch. Loki went to follow suit when a hand covered his mouth and started to drag him in. Loki pulled the hand away and pushed himself away from the man, only to find himself falling out of the carrier. It took Loki a moment or two to stop spinning as he hurtled towards the Earth. Loki looked around for something to slow his decent, but he spotted nothing. He found himself snatched out of the air sliding down a building. Loki looked around fanticly until he saw who had saved him, he felt his heartrate go up as he saw the Hulk.
Hulk tossed Loki to the ground and went to find the Avengers. Loki watched until Hulk was out of sight. Loki stood there, not sure what to think, or do, or say. Just standing there. Loki looked down and spotted a shotgun. He got a grin and picked it up. He's not out of this fight just yet...
...
"That guy had way to many tricks up his sleeve, which one of you took him down anyway?" HawkEye asked. no one spoke.
"Um, guys," Natasha picked up a note laying on the man's stomach. "It says: He's all yours. Loki." Everyone just stared at the note in her hand. HawkEye raised his bow and everyone else their weapons as well.
"Speaking of the devil," Tony stated as Loki walked onto the scene. He hadn't completely noticed the Avengers yet, he knew they were there, but he didn't look up at them. He tossed the gun he held to the side. He looked at the body and then up at the Avengers. Natasha smacked him. Loki looked at her, not exactly angry but close.
"You know what that's for," she hissed as she walked over to the others. Loki put his arms out in a funny way. He looked so weak and tired.
"Just kill me and get it over with," he said, slurring his words a bit. He looked down at the ground, ready to die. Loki was genuinely surprised when no one opened fire. He looked up at them to find they weren't looking directly at him. HawkEye pointed his arrow down and a few others stopped aiming at him. Thor and Tony didn't back down though. Suddenly Loki heard Hulk roar from behind him and they also put their weapons down. Loki cringed a bit. Last time the had met up...
Hulk picked Loki up and held him in his arms in a tight hug. Loki grunted. That happened the last time he saw the Hulk. All of the Avengers looked very surprised at this, Hulk liked Loki? Loki gave a small smile.
"Yeah, missed you too Hulk," he said. "Can you put me down now please big guy?" Hulk set Loki on the ground and patted his head twice, like he was some kind of dog. Loki looked at the Avengers, all of which were looking back in confusion. "You dont wanna know why, and no I wont tell you."
...
Not my best work, but I'll go with it