Everything I write is sad. Why not something cute for once?
As per usual, none of this is mine yet. And I am my own editor.
'So, without further gilding the lily and with no more ado, I give to you,' the story!
Tony woke up in the lab, slumped on a high stool, his face pressed flush against the cold table. He lifted his head groggily, blinking into the darkened, empty room. Someone had draped a blanket or something over his shoulders - upon examination, he discovered it was Bruce's lab coat. He pulled his arms through the sleeves of the coat and looked around, realizing Bruce must have dimmed the lights for him.
"Bruce?" Tony called out, not seeing the physicist anywhere. Tony shrugged to himself and wandered out of the lab, ordering JARVIS to turn the lights out as he left. He hesitated in the hall for a moment, hearing soft noises coming from the living room down the hall. He turned and went in that direction instead of towards his bedroom, rubbing his chin and yawning as he went.
When Tony got closer, he caught sight of Bruce walking back and forth across the room tiredly, his head bent and his arms holding something that he was talking to. It didn't take long to realize it was his son. Steve was sprawled on the sofa, observing Bruce and the infant with subconscious interest.
As Tony watched, Bruce yawned widely and continued trying to get his son to fall asleep. Steve got up from the sofa after a moment, standing in front of Bruce. Bruce's pacing and bouncing stopped while Steve bent down over the infant, saying something in low tones before looking up at Bruce. Bruce nodded in response and transferred the baby to Steve.
Steve held the baby upright so his small head was resting on Steve's shoulder. He was saying something softly; Tony guessed he was singing an old song. Bruce scratched the back of his head as he yawned again and watched Steve.
Thor came in then, brandishing a bottle of something and promptly taking the baby from Steve. He began feeding the infant the way Bruce had showed him, trying to be careful, his deep voice carrying but still not clear to Tony. Bruce adjusted Thor's arms, keeping his eyes on his son protectively.
Steve laughed after a moment and stole the bottle from Thor, teasing the baby with it. The infant began laughing, and the sound seemed to attract Clint and Natasha from the kitchen Thor had just came from.
Natasha held her arms out to Thor, and the Asgardian obliged, placing the infant in her arms. Clint slung an arm around Natasha's shoulders, making faces at the kid while Natasha swung him back and forth gently. Bruce said something softly, smiling at Natasha as he did so. Natasha looked up at him in surprise, but Clint just pulled her closer.
Tony really just did not want to interrupt this, for once. Steve moved in front of Natasha and was saying something to the baby as though he would receive an answer. Thor, attempting to keep his voice down and only just succeeding, was talking to Bruce about something. Bruce shrugged and nodded when Thor stopped talking, and the God grinned widely.
Natasha shuffled slightly before she passed the baby over to Clint, who seemed unsure of what to do. He held the baby as Natasha had and just looked down at him. The others all fell silent and watched him curiously.
After a long moment, Clint cleared his throat and asked Bruce a question. Bruce stepped forward, pushing his son's dark curls away from his small face, smiling as he answered Clint's question. Clint shifted a little and turned his head to look at Natasha, who just met his eyes and smiled a little.
Bruce was still moving his son's hair, dragging his fingers lightly through the tangled strands, so Clint laughed and returned the baby to him. Thor announced something in his booming low whisper that was maybe a question, and Bruce's downturned face flushed dark red, and his heart monitor beeped a few times before calming. Clint and Natasha both turned to Thor in surprise; Steve, however, turned to Bruce worriedly - or, rather, he was watching the child in Bruce's arms, not Bruce.
Bruce looked like he was going to snap at Steve for a moment, but he took a deep breath and said something softly instead. Steve looked guilty for a moment before he clapped his hand on Bruce's shoulder and told him something firmly. Bruce nodded in response, and Steve left, taking off down the opposite hallway.
Thor followed soon after, then Clint, then Natasha, all of them saying something to Bruce before they went. Thor gave him some sort of hug, Clint smacked his arm, and Natasha kissed him on the cheek. Once Tony was sure they were all gone, he entered the living room from his hiding place behind the wall and approached the exhausted Bruce.
"Hey." Tony said, trying to keep his voice down. Bruce looked startled for a moment, his heart monitor beeping twice before stopping. He shot a glare at Tony.
"Don't you sneak up on me right now." Bruce said as menacingly as he could. Tony laughed.
"Thanks for the threat, big guy." Tony replied before coming up in front of Bruce and, just as Bruce had done before, began pushing the baby's curls out of his face. "He looks like you, you know."
"I know." Bruce said, his voice low. The baby and Bruce's chest were bathed in the sharp blue light of Tony's arc reactor, but the child didn't seem to mind too much. He turned his small face into Bruce's chest, yawning widely. Tony looked up at Bruce's face, surprised to notice he looked like he was on the verge of bursting into tears.
"You okay, Doc?" Tony asked quietly. Bruce nodded and smiled at his son before looking up at Tony.
"I just never thought I'd have a family, you know?" Bruce's voice cracked slightly, and he turned his face back down to his son.
"Yeah, I know." Tony replied, keeping his voice soft. He thought back on the team, the Avengers who had just left the room. "You have a family now, buddy."
Bruce smiled up at Tony, and, before Tony knew what he was doing, he had thrown an arm around the physicist's shoulders. Bruce leaned into his hold tiredly, yawning and closing his eyes.
"Thank you, Tony." Bruce said, his voice sounding exhausted. Tony just nodded.
"Thank you." Tony said in return, allowing the rare moment to sink in and take ahold of his heart for just a little while.