One time, when Peter stayed at the compound, he had dropped oil all over his sweatshirt. So Tony being Tony, called Steve down with one of his. Of course, Bucky tagged along. As soon as Steve saw Peter's sweatshirt, he went full on mama mode. He started doting about the stain while pulling the sweater off of Peter, who was flustered. Then, he put Peter in the huge sweatshirt. Peter glanced up at him with a sheepish smile and lifted his hands. They were covered and some of the fabric went over.
"Sweater pawsss," Peter drawled out as he spun in his chair. Tony's heart melted. The kid looked so adorable. One look at the two other men in the room confirmed that they thought the same. Steve and Bucky left to take care of the sweatshirt.
They returned to working, Peter constantly shoving the sleeves up his arms as they kept falling.
It was around 3 AM, but neither of the two boys knew that. They only knew that one of them was tired. Peter. Peter was tired. So he was passed out on the couch in the lab. Tony walked over with the blanket they kept down there and tucked him in. he stopped though, when he saw something. He picked up Peter's sweater clad hand and smiled softly.
"Sweater paws," he whispered before setting it back down and going back to work.
Steve never got his sweatshirt back.