I've said it before, and I'll say it again:
Ozzy is just a traditional Egg Stealer who was getting REALLY ANNOYED with the same kids interfering with his plans. Sierra, on the other hand, was a full-blown psychopath. There's no other reason why he would suggest feeding hatchlings to Sharpteeth out of the blue and frightening Pterano.
I'd have almost said that aobut Ozzy, but how he treats Strut says otherwise.
Plus, Ozzy hoped the kids had been eaten by the Chomper shadow. He's no better than Sierra in that regard.
Plus, he wanted to give them lava baths and throw Littlefoot off the Great Wall.
Also, Ozzy is a control freak. He always likes things his way. Even wehn Strut is hungry and is even begging to lick a leaf, Ozzy says no and keeps taking it from him.
Plus, if you recall, Ozzy said Strut needed to eat eggs, yet, when it looked like he'd won, HE, not Strut, was about to eat it.
Also, recall that all Ozzy was after was a stupid egg but what Sierra was after was, as far as he knew, a stone that could let him take over the Great Valley. Hence that might give cause for his more extreme behavior by comparison to Ozzy.
Ozzy's insults were at HIS OWN BROTHER. Would Sierra sink that low?
Also, Ozzy's effects on Strut are also telling. At the beginning of 2, Strut would be content just to have green and was talking Ozzy out of his obsession with eggs and later tried to talk Strut out of harming the kids.
However, as the film progresses, later Strut is seen laughing kinda freakishly as Ozzy and he advance toward the kids. Later, HE is the one who suggests MURDERING Littlefoot. And, right before the end, Sturt is about, HIMSELF, to MURDER Chomper.
It's not like Sierra has such a melovant auro that he was able to get his own partner, Rinkus, to go from being kind and subservient to murderous.
While Rinkus faked being such, he was truly a stinker all along. Strut, on the other hand, could well have been accepted into the Great Valley as a Friendly Egg Stealer had his brother not been around. By the end, Sturt is getting closer to Ozzy's level of nastiness.
As for Sierra, he was power hungry. He wanted that Stone. Also, for all he knew, the kids might be leading the grownups to follow them, hence foiling his scheme, and, seeing the kids, wants to get rid of them for daring to mess with him.
As for him wanting to kill Ducky so bad, she had overheard his plans and he might have believed that dead Duckys tell no tales. True, he's got less self-restraint than Rinkus.
As for how Sierra actually plans to feed the kids to the Sharpteeth, he might have just been talking out of his butt. He could only throw Ducky to a Sharptooth. Petrie can fly and the others would be kinda heavy for him to grab and fly off with, especially if they struggled.
Plus, Sharpteeth have the habit of going after ANY edible food source, which would INCLUDE Sierra!!!!
Not that I'm suggesting that Sierra isn't a psychopath, he clearly is.
