Ducky: Petrie, why are you looking at me like that? I don't want to be bait! I thought you loved me, I did, I did. 
Petrie: 
your world is ruined, Impractical.
It appeared that Petrie sympathized Ducky all the time only to sacrifice her to save his life when time of great danger comes.

And Littlefoot did too... Now I understand, why in their meeting scene he didn't want to bring her with him, but out of sudden he changed his mind. With wily grin on his face... :O