Lure it to a large body of water and tie some weights around it’s neck
Keep doing the thing where you tap one of it’s shoulders and quickly hide behind the opposite one, eventually it will become so infuriated it will breathe fire on itself and perish
Tame it, tickle it, fuck it
Put some dragon food in a seemingly innocuous looking spot but there’s a large net above the food and then you drop the net on the dragon when the dragon goes to the dragon food
Put your differences aside and work it out like grown ups
Ask it if it’s proud of itself and its life choices. If it was a child dragon again, would it be proud of the adult it had become?
Challenge it to a game of Mario Kart (claws too big for the controllers, it’ll be rubbish but its pride will make it think it’s better than it is).
Say “Stupiddragonsayswhat” really fast and then when the dragon says “what?” say “ha, you’re a stupid dragon”.
Ask why it’s not as cool as the dragon from the Welsh flag. Keep looking it and then a Welsh flag you’re carrying with you and look disappointed whenever looking at the dragon.
GIve it an annual performance review and focus only on the negatives, citing massive areas of improvement which are required.