Headcanon that Groot’s habit to bring everything but what he was asked to bring one day lets him return something everyone has already forgotten about.
One day, Peter absentmindedly asks Groot to bring him a tool while he’s working on the Quadrant’s repairs, and Groot vanishes for a while, returning with stumbling little steps and his found proudly presented. “I am Groot!”
“Thanks, buddy,” Peter mumbles, reaching over – and hesitates as his fingers close not around a smooth handle, but a flat little thing, cool to the touch, one end round, the other spiky.
Heart suddenly in his throat, Peter uncurls his fingers and draws a shuddery breath when he sees the familiar flame-badge on his palm, fairly out of place when it’s not attached to an equally familiar red coat.
Groot looks up at him with big eyes.
“Groot?” Peter is horrified to hear his voice crack, but it’s better than the howl that is building somewhere in his chest which he is fighting down with all his might. “Where… where did you get that?”
It’s a dumb question, he knows the moment he utters it, because Groot is a baby, he won’t be able to answer him, probably didn’t even understand the question, and besides, there is only one person who was in possession of this badge, who would have been able to give this to the toddler, but still, Peter’s mind reels, because – when, where, why, why did Yondu give it away, he would never have given it away unless….
A gentle touch to his cheek draws him from his jumbled thoughts, and Peter blinks down at Groot. The baby has sprouted a vein long enough to touch Peter’s face, carefully catching the tears streaming down. “I am Groot?”
Peter laughs, the sound a garbled mix of a sob-chuckle. “No, Groot, you didn’t do anything wrong.”
Groot frowns, seemingly not convinced, but pulls the vein back. Instead he reaches out with both arms, upwards, a silent demand. Peter obeys, letting the toddler crawl onto his free palm and lifts him up until they are on eye-level, Groot able to cuddle to the Terran’s cheek.
After a moment, Groot croons, stretching his hands out for the badge, and Peter only hesitates for a second before handing it over. The badge secured in the baby’s arms, Groot turns, blinking up at Peter with an expression that is too serious for a child. “We are Groot.”
It’s too much, another blow to something already fragile, and Peter breaks into tears then, even though he can’t help but laugh about the irony of all of it at the same time – it’s a fucking badge, a bit of metal, and he finds himself crying over it like a baby, stupid, stupid, full of sentiment….- but he can’t stop, all the tears that he has swallowed down the whole time breaking free.
If Groot minds getting wet, he doesn’t complain, just wraps his tiny arms around the badge and whatever he can reach of Peter’s face while he croons and mumbles and tries to comfort as best as he can.
Groot doesn’t understand as much as an adult. But he understands what “family” means.