We already know what happened to Skylynx and Darksteel, but what about Predaking? What has happened with him now that he's truly alone? What about the time that Optimus Prime and Windblade encountered him on Earth (after the war was over)?
Dear Predacon Perceptive,
After his battle with Starscream, Predaking abandoned Cybertron. He had no real ties with the world, and with his kind largely extinct, he felt he had no reason to remain. Taking Starscream's arm with him as a trophy, he traveled to Earth—which he felt was his true home—and as you noted, he encountered Optimus Prime and Windblade. Though they fought briefly, neither he nor they particularly cared to see the fight through. However, when Predaking realized Optimus had stolen his trophy, he was incensed, and flew to Crown City to avenge what he felt was a cowardly slight.
Taking roost atop the Crown City Colossus, Predaking roared a challenge to the Autobots, who at that moment were occupied by an argument between Strongarm and Sideswipe; she'd accused him of stealing her Decepticon Hunter. They jumped into action, taking a GroundBridge to Crown City Bay. Denny and Russel Clay assisted in closing off the area, claiming to bystanders that a monster movie was being filmed, and that Predaking was merely a very advanced animatronic—which was great news for Grimlock, who was able to leap into battle without any disguise, and engage Predaking beast to beast.
With Strongarm and Sideswipe still fighting over the Decepticon Hunter, Bumblebee and Optimus were the only ones really helping Grimlock in battle—and unfortunately for them, Predaking was just as fearsome an opponent as ever. It was only when Sideswipe admitted that Strongarm's Decepticon Hunter was actually with Fixit for repairs, after he'd pinched it for an ill-conceived dual-wielding stunt, that Optimus realized why Predaking was calling them thieves. He knelt in surrender to the Predacon, and as he no longer had Starscream's arm to return, he prepared to detach his own in reparation instead. Predaking, inspired by this act of self-sacrifice, declared the quarrel over, turning down Prime's arm before taking to the skies once more.
Predaking continued his life as a hermit, refusing all petitions for aid and asking none for himself, and the legend of the Dragon of the Sierra Vistas passed into local folklore. But this solitude couldn't last forever. Years later, a new group of Rescue Bot recruits ended up training in the Sierra Vistas, learning how to perform wilderness rescues by searching for their "lost" instructor, Grimlock.
Predaking, naturally, was still not particularly fond of intruders. When Slash went off alone, he trapped her in a gorge, and he was able to pick the rest off one by one when they split up to look for her. In the end, the rescuee became the rescuer, with Grimlock charging into action once more when he recognised Predaking. He claimed that the recruits had every right to train there—until Predaking pointed out how close the recruits had come to damaging the archeological sites of the area's indigenous tribes. He had only imprisoned them to ensure the sites' preservation.
Grimlock realized he had fallen back into his worst habits, and apologized, asking what had made the Predacon so interested in the Sierra Vistas' former inhabitants. Predaking explained that he felt a kinship to them, and that he had decided to become their guardian. In acknowledgement of this, Grimlock arranged with the other Autobots for Predaking to become officially recognised as a Rescue Bot, to rescue indigenous sites and people from exploitation.