Yep, captain bubbles!
I had Vinca roll animal handling checks to make sure the egg hatched properly, and then roll another check each day to keep it in control. Failure meant that the greenspawn would act extremely aggressive and greedy, potentially even lashing out at the players. Basically I played baby Bubbles like someone trying to tame a somewhat intelligent, very greedy cornered feral cat. Except the cat is a cross between a green dragon and a Scyther. So difficult and needs a lot of attention and care, but can be done. I think the DC started at 25 and went down as you tamed him though this was 3.5. There was also lots of roleplaying involved; sadly I don't have the time to go into details now because finals.
Also that ending was glorious.