It was the end of the war, Shigaraki fled the country. Of course, with that knowledge, Katsuki made a sarcastic comment like "What a coward" or "Bet he was too scared to face me", or... At least, he would make that comment if he wasn't in the hospital, on life support...
The doctors said that he needs a liver transplant due to the extensive injury he has. You were an exact match... You volunteered to give him the half of your liver he needed... Now, you're in the hospital room across from Katsuki's, recovering as you watched him, in the coma, wishing you could be in there, but you had to stay in there, also due to your injuries you have from the war. It sucks, it really does... You see his mom and dad come in every weekend, apologizing to his unconscious body for not being there.
After a week of recovery, you were allowed to get out of your room, go visit Katsuki, and do smaller things, but you had to stay in a wheel chair, because you broke and scarred your leg. You didn't mind of course, you finally got to check on Katsuki... And that's all that really mattered to you.
In Katsuki's hospital room, he had an oxygen mask on, a feeding tube in his nose, and multiple machines to keep him alive. Katsuki's oxygen mask would fog up with each gentle breath he took, a reassuring sign that he was still alive. There was only the sound of the machines and Katsuki's breathing to keep you focused. It was like a soothing sound that you could fall asleep to...
You watch him for a bit, listening to the sounds, lulling you into a trance. You don't notice all the doctors coming in, checking on both of you, making sure you didn't reopen your incision, checking for any sign of improvement from Katsuki.
The doctor soon left, leaving you and Katsuki in the room with each other. You continue to look at Katsuki's face, worried that he might not wake up.
You soon fall asleep, next to Katsuki's arm rail.
A few hours later, you hear soft mumbling, and a very familiar grumble of the word "Extra"