Leveling the Pet Baby Dragon?

[Deviation]

So Ages ago my PCs decided to not kill the baby dragon they were sent to kill as part of a quest and, instead, chose to befriend and tame/bribe it by feeding it gold and gemstones (they feed the dragon gold. it's hilarious) But now we're at a point where My PCs are just hitting level 8...and the baby dragon is still CR2. Any advice on how to effectively make a slightly beefier baby dragon without using Young Dragon stats? I'm looking for something in between- something that reflects that the Dragon has grown with them but is still effectively a child. I'd rather not force a tearful good bye because tbh I love playing a baby dragon that eats gold and learned to curse in Orcish. I'm also using Baby Dragon as a hidden morality tool- Morality is important in my campaign and by effectively raising this baby dragon it'll grow to reflect the views they taught it (next session I'm gonna have the dragon try to kill someone slimy but not deserving of death for the reason of "but don't we kill things that anger us?")

TL;DR- subtle ways to show a baby green dragon has grown/learn without using Young Green Dragon Stats?

[the_david]

I suppose the simple answer is to make in between steps of either a +1 to its CR or +1 hit die. Its abilities should grow along bit by bit. I don't think it's that hard to do.

[laserswords]

Seems like a cool way to give the players some choice, too. Maybe they a local innkeep can tell them eating fish makes them deal more damage, whereas eating land meat makes them gain more health? That way you can give the party some customization and control over the dragon.

You could even take this to the next level, and make a little skill tree, where players can choose together the "perks" the dragon has learned at the end of a session. Bonus to initiative vs bonus to speed, good at finding gold vs good at finding loot, etc.