@mcv They need to be 14 because that's their age! (I wasn't talking about level)

D&D's core Combat Thing is the Action Economy. So if you have a Dragon, it can hit 1 person for 1 hit per around (modulo some things), and the players can do more. If the Dragon spends its turn healing, then it's likely to do less healing than the players can dish out in a round, so the dragon just wasted a round.

If the dragon focuses on PC, that's gonna suck because that person is likely to go down, and, whittling through their HP is gonna make the dragon run out of HP, but now you have 1 PC having a bad time, and everyone else an anticlimax. D&D fights with single enemies are basically *entirely* anticlimax.

And - yeah - listening in is hard - but I recommend trying.