Some TMNT stuff was always meant for grownups.
In Eastman and Laird's Teenage Mutant Ninja Turtles, a certain unnamed Triceraton first appears in volume 1 issue #6: The Triceraton Homeworld, and is later individually introduced in volume 2 issue #10: Descending into D.A.R.P.A., playing an important role in the next few issues of that volume.
In volume 1 issue #6: The Triceraton Homeworld, three random Triceraton commandos in the Tri-Sports Arena were ensnared along with the turtles and Professor Honeycutt by a transmat beam opened by the Utroms at TCRI to bring the turtles back to Earth. The turtles were the only intended targets; Honeycutt and these three Triceratons were transported accidentally.
In issue #7: All is Revealed, the three stranded Triceratons realized they'd been transported to an Utrom transmat, and their first priority was to seize the technology for the Triceraton Republic. The Utroms of TCRI used their weapons to stun the Triceratons unconscious, but they could not remain a focus of concern as the facility was already under siege by the National Guard, mobilized after the very public spectacle of the first transmat beam that had previously sent the turtles to D'Hoonnib. Amidst the chaos that followed, most of the Utroms escaped along with the turtles and Hamato Splinter through the transmat and destroyed TCRI behind them. The fate of the three Triceratons was left uncertain.
One of the three was Zog, who played an important role in issues #19: Return to New York, Book One, #20: Book Two and #21: Book Three along with Tales of the TMNT volume 2 issue #70: Zog. Zog's fate revealed that Triceratons cannot breathe Earth's atmosphere indefinitely, as it will poison them to the point of dementia, as happened to Zog over time.
It was not until volume 2 issue #10: Descending into D.A.R.P.A. that the fate of another of the three Triceratons was revealed. This individual, who was never introduced by name, had been captured by the United States government and confined to a stasis tube into the top-secret DARPA facility. The recently abducted Raphael freed himself from his restraints and found multiple such stasis tubes confining different aliens, including the Triceraton. Raph was soon recaptured by human guards.
In issue #11: The Rescue, a group comprised of Leonardo, Donatello, Michelangelo, Casey Jones, Louis Braunze and Nobody had been infiltrating DARPA to rescue Raphael. They came across the stasis tubes and released their alien inhabitants. As soon as the Triceraton awoke inside his tube, he broke out of the glass, spilling out with the tube's liquid contents. (Since he had been in stasis until now, he wasn't yet suffering the same atmospheric dementia that had stricken Zog.) He recognized the four turtles as his adversaries of years ago, but the allies and aliens put aside their differences to cooperate and find a way to escape. The enlarged group of allies came across a room with some of the aliens' confiscated gear, and the Triceraton quietly realized that one of the objects is a Triceraton sub-space homing beacon that was not only still operational, but had already been activated, meaning Triceraton reinforcements were already likely on their way to Earth.
In issue #12: The Escape, the previously naked Triceraton had dressed in a pair of briefs and now wielded his energy rifle. With a fighting chance for survival, the group began their escape. Initially they fanned out to examine the corridors and secure an escape route. The Triceraton partnered with Michelangelo and another unnamed alien and went off in one direction. At a branch between a corridor and a stairway, Mike split off to check the corridor, leaving the two aliens to check the stairwell where they were soon attacked by some guards. Once the two aliens established that the stairwell was secure, the duplicitous Triceraton killed his alien partner, and falsely explained to Mike that the alien had been killed by the humans. After regathering, the group proceeded through a cave, losing Nobody to a giant starfish before an explosion along the cave's roof revealed sunlight and the surface, where human soldiers were already waiting for them.
In issue #13: The Battle, the group took cover inside the cave, but heard new explosions on the surface, where they discovered that the human soldiers were under attack by Triceraton reinforcements. The erstwhile Triceraton ally turned on the rest of the group, shooting and mortally-wounding Braunze. As Leonardo rushed to Braunze's side, the psychic Braunze revealed to Leo that he could sense that the already ill-equipped Triceraton reinforcements were facing defeat, and planned a suicide run to ram their dilapidated Triceraton asteroid ship into the Earth at high speed right on DARPA's location with an impact that could kill thousands. The treacherous Triceraton overheard this and immediately called it a lie, believing the Triceratons' empire was destined to conquer and rule Earth for all time. As he said this, a Triceraton attack vessel in the sky had been shot down and was quickly falling to the ground behind the one Triceraton's vision. He taunted his former allies to run before Earth's new rulers; they indeed ran, but to avoid the crashing vessel just as it fell on top of the unaware lone Triceraton, killing him instantly.
- In the original 1994-1995 editions of Mirage TMNT volume 2, this along with all other Triceratons shown were depicted with golden brown skin, with the lone Triceraton at DARPA wearing green briefs. But the later IDW Publishing reprints of this volume applied completely new colors to all 13 issues of volume 2 with the recoloring outsourced to Digikore Design Limited, and all volume 2 Triceratons up through issue #12 were depicted with blue skin, with the one Triceraton wearing fuchsia briefs. But in #13, the reprint inexplicably altered several of the character palettes, changing all Triceraton skin tones back to a golden brown color, with the one Triceraton again wearing green briefs. This is especially curious as the reprints of issues #10 through #13 were reprinted together as Teenage Mutant Ninja Turtles: Classics Vol. 10, meaning the palette change happened partway through the same trade paperback book.