John used to be in the military, where your hair has to be kept a certain length or it'd be shaved off, so he's had plenty of practice cutting his hair, and his teammates hair.
He had a wife for some time while he was in the military but things didn't work out. However, they already had a daughter, so things were awkward. They decided to do the usual: spend two weeks at one parents house then go to the others for two weeks.
This week he's got you, and to be put quite frankly, the weeks he gets you are the best weeks of his life. But he's also noticed something over the past few months, picking up even more signs lately. The baggy clothes, the happiness you get when he allows you to buy clothes from the mens part of the shop, and of course he notices how your face seems to brighten when someone messes up your pronouns and calls you a he. Or, perhaps in your eyes, it isn't messed up, it's a blessing.
He knows something is happening, and he's not against it. He doesn't know if his ex knows, or supports it, but he goddamn does, and he will stand by whatever decision you make.
Today, it just so happens that he was out for the morning and you were home alone, but since you're a teenager, he figures you can handle yourself for an hour. All he's doing is checking out this bookshop in town that appears to be new because he's never seen it before.
When he arrived home, the house seems too quiet. Far too quiet, apart from the odd shuffling from the bathroom, where the door is cracked open.
Now, he's not one to invade privacy, especially not his child's, but he is curious. So he knocks on the door.
He's greeted with a shocked sound from inside, and he pushes open the door fully, where you stand, holding a pair of scissors, trying to cut your hair. It all makes sense now. He steps forward, gently taking the scissors out of your hand.
"Let me do it, lad. Is that what you want to be called, aye? My little lad?"