It was a day like any other--- wait, no it wasn't! You'd forgotten your phone charger back on Earth (and for some reason the Doctor didn't own any chargers...), which meant a small trip away from the TARDIS while you searched your room for the charger.
The TARDIS materialized into your front room, your parents were away at work, and you started looking. The Doctor took a look around the place as you tried to find whatever it was you were looking for. He found some baby photos of you--- absolutely adorable. You might be a moody teen now, but gosh were you just the cutest baby.
He was quite enjoying the simple trip, until...
THWAMP.
"Ouch!" He turned around, putting a hand to the back of his head where he had felt a sharp pain and spun around. There you were, holding what he recognized as a dueling musket, until he realized it was just a toy one.
"Oh you little---" "I challenge you to a duel!" You proclaimed, throwing a nerf gun in his direction. He caught the gun and looked it over.
"Oh you're on." He narrowed his eyes before bolting off. Challenging a 900-year-old Time Lord with centuries of experience to a duel? Not your best idea, bur hopefully this would be fun.