Chromedome was one of those background characters no one really cared about. I had the toy long ago, but it was far from my favorite. He was one of the original “Headmasters” where the head came off to turn into a little guy. He appeared in the “Rebirth” miniseries of the American cartoon and in the Headmasters miniseries of the Marvel comic, but he was never really important.
He gained more notoriety in the More Than Meets the Eye series from IDW. He’s one of the Autobots who follows Rodimus Prime to search for the “Knights of Cybertron” out in space. Chromedome comes in handy as he has the unique ability to access the memories of other robots, sort of like a Vulcan “mind meld” on Star Trek. This backfires in a couple of issues when he mind melds with the psychotic Decepticon Overlord, who escapes and goes on a rampage, killing Chromedome’s roommate and “special friend” Rewind.
Though there’s never any sex shown between them, Chromedome and Rewind were pretty much a couple. They were often like an old married couple in their bickering. After Rewind dies, it’s revealed Chromedome has had a series of such special friends, all of whom died in the war. Using his special ability on himself, Chromedome would wipe his memory of that friend so he wouldn’t have to endure the pain.
That’s how you take a largely useless character and make him more important.
Cyclonus made his first appearance in the 1986 movie. He’s the recycled form of one of the old Decepticon jets (Thundercracker or Skywarp) that Unicron gave new life to help destroy the Autobots and capture the Matrix of Leadership. He survived the movie to be Galvatron’s most loyal henchman. A few times he fought Ultra Magnus, with whom he shared a special bond as they were both loyal soldiers with their own code of honor.
He didn’t really appear in the US comic book much. Like Chromedome he gained a more prominent role in IDW’s More Than Meets the Eye series. Again Cyclonus is an honorable soldier, but with the war over he decides to join the Autobot expedition. As one of the older Transformers on the ship, his knowledge of “Old Cybertron” sometimes comes in handy. He grudgingly befriends the tiny Autobot Tailpipe, though he’d never actually admit they were friends. When Tailpipe is dying from a rare disease, Cyclonus gives him a transfusion of energon to help save him.
Besides the original toy, he was reissued as a “Targetmaster,” which was the same basic toy only he had a gun that turned into a little guy. In the “Rebirth” miniseries it was kind of stupid how when the fighting started Cyclonus would toss his gun away so it could turn into the little guy, essentially leaving him weaponless. He's been reissued a few times since his original model.