There could be kidnapped by dil and itchy and the gang go out and try to save them. But thnking about it I don't think that would happen.
Capturing or kidnapping are tricky elements for LBT. I have been using something like that in an LBT story in which Ozzy and Strut captured but didn't kill Littlefoot and Ducky hoping to catch the others too when they tried to free them. There are not many scenarios in which this works in LBT (my own was not exactly credible I think) because most "villains' villany" in LBT is based on eating the main characters so keeping them alive or "imprisoning" them would often make little sense to the "villains". Possible motives might involve using "captives" as baits or for some kind of revenge plot. Villains we have seen so far with whom this might work out would be Ozzy and Strut, Rinkus and Sierra.
Keeping any of the LBT characters in captivity too might be tricky though. And require one of the villains at least to guard the respective character all the time. In case of Ducky and Petrie it might be possible to "lock them up" by making up a "prison" with rocks too heavy for Ducky or Petrie to move.
In case of Littlefoot, Cera and Spike it would be very difficult though. In fact I think they might even be too strong / massive to allow Rinkus or Sierra to force them to anything at all.
Technically, we already did see Ducky kidnapped in VII.
Also, who says the villains won't want to eat the characters once they all come? I mean, what if they tricked Chomper into coming, as meeting the first Talking Sharpteeth, other than himself, in the whole wide world might peak his interest and Dil and Ichy could take him prisoner.
Littlefoot has jumped in water with a Swimming Sharptooth in it to save Chomper before. He would definitely go into the Land of Mists to save Chomper, and, as for Ruby, well, she might be wondering how she's gonna explain to Chomper's parents why she lost him (and possibly fear that they'll eat her for letting them down) and so she'd go too. If Littlefoot and Ruby go, the others might come too.
As for a trap situation, it's kind of like in the original Narnia story, where the White Witch tried to get Edmund on her side, trying to get all four kids. Later, she might have hoped that they'd come after their brother and walk right into her trap.
I mean, Dil and Ichy might want the whole Gang of Seven to eat. Getting one might bring others. They just have to gag Chomper so he doesn't talk when the others get too close and try to warn them.
I did have a fanfic idea where Rinkus and Sierra, who are creepy enough to go there, met Ichy and Dil there and Sierra decided that he was gonna make good on his promise to "feed them overgrown eggs to the Sharpteeth". This would take place during the TV Series though Dil would be outside the Great Valley with Ichy, Rinkus, and Sierra just flying over the Great Wall and chasing the Gang of Seven outside the Great Wall. It would be even more amusing if the four villains thought Chomper might be an ally and tried to recruit him before learning of his true loyalties. I had Pterano just happen to come back from banishment and Guido just happen to be flying overhead and foil the bad guys's plans.
Eventually, Rinkus and Sierra would break up with Dil and Ichy. Rinkus and Sierra would vow to get even with Pterano, Guido, and the Gang of Seven. Dil and Ichy, meanwhile, would wisely decide NEVER to go after the Gang of Seven ever again.
Also, in a fanfic of mine that involved an older Gang of Seven, I had Chomper where he'd been kinda put in a jam by a conniving villain where he basically had to attack a Leaf Eater (the Old One) or watch his girlfriend die. He chose option 1 and the Old One died from her injuries and he nearly went nuts and almost ate her. He then had to scamper from the Great Valley.
Then, to make things lousier for Chomper, his girlfriend's home got taken over by Red Claw, who, pointing out that Chomper still wouldn't renounce friendship with Longnecks, had gotten Chomper chased off. Also, it appeared that Red Claw had killed his girlfriend's parents.
With Leaf Eaters, believing that Chomper was guilty of the crimes that the conniving villain had done, on a massive dino hunt for him and Red Claw's goons on the lookout for Chomper, not to mention minions of the conniving villain, Chomper and his girlfriend were dodging foes everywhere. Eventually, they were able to hide out in the Valley of Mists, where they lost their pursuers.
Chomper would sit here and think his life over, wondering whether to somehow, though very unlikley it was, to get back into good graces with the Great Valley and rekindle his broken friendship with Littlefoot or whether he should, given the circumstances, finally accept his long rejected life as a Sharptooth hunter of Leaf Eaters.
The mists could even symbolize the indecision that plagues Chomper. He would almost drift closer and closer to making a decision against Leaf Eaters here, with his girlfriend telling him that she'll accept him either way.
Chomper would meet Dil and Ichy, again, here. However, he'd decide to bury the hatchet and not start a feud with them for the Rinkus and Sierra incident years earlier. The four would form a hunting group. Eventually, Chomper appears about to accept being a "bad" Sharptooth, and tells the other three to go get him meat, as he still can't bring himself to hunt Leaf Eaters personally yet.
However, events would transpire to stop him from going over, shall we say, to the Dark Side. I really don't see how any Leaf Eater would want to go back to the Land of Mists. If even the veteran Old One was afraid of it, it must be really bad. The Gang of Five and Ali were just really lucky one guesses.
As a fifteen foot fall creature with at least foot long teeth, Chomper wouldn't have too much to fear there and so would be relatively safe. (Also, he has a girlfriend and later Dil and Ichy too, so he's safe from big preds.)
