"If I die young,"

Steve looks up from his sketchbook to see YN standing in the kitchen of the new Avengers Tower singing.

"Bury me in satin"

"Lay me down on a"

Natasha turns around too and watches YN with Steve.

"Bed of roses"

As YN continues singing, Tony looks down facepalming muttering, "Not again."

"Sink me in the river"

While YN sings, Steve asks the others, "What's with the song?"

"at dawn"

"YN wants us to sing this song when they die," Vision replies.

"Send me away with the words of"

Natasha looks at YN again and says, "You're not going to die young, YN."

"a love song"

"That what I said!" Tony shouts.

Steve says, "Don't overthink it," knowledgably.

YEARS LATER (during Endgame)

Peter finds YN at the end of the battle and crouches in front of YN looking at her flickering Arc Reactor in the suit given to her by her dad. He silently begs, "Please don't die YN! I can't lose you too! I love you!" He realises that your dying when it takes YN some time to reach out and grab his arm and he starts singing shakily looking at her Arc Reactor somewhat unable to look into his dying girlfriend's Y/E/C eyes.

"B-bury me in satin"

"Lay me down on a bed of roses"

Pepper and Tony notice and join in...

"Sink me in the river,"

Then Steve joins in

"At dawn,"

Thor and the others who are still alive join in for the last part.

"Send me away with the words of a love song."

Peter covers YN's flickering Arc Reactor looking into your Y/E/C eyes normally full of life, love and laughter, unable to look at the Arc Reactor when it is signalling that your dying.

Finally, it flickers out and Peter gives you a kiss on the head followed by Tony and Pepper.