Some TMNT stuff really isn't for little kids.
In his Mirage incarnation, Marlin is shown to be a very stubborn and tenacious hunter, who never allows himself to be diverted from his prey. He is after only "exotic" prey and cares not a whit about how his victims must feel or whether they are capable of feelings at all (e.g. Leatherhead).
Marlin also doesn't seem to be very sociable at all. Except for temporary allies (such as Razorback) or hired helpers, he has little support (and usually not for very long) and instead names his hunting rifle affectionately "Betsy".
Mr. Marlin is a rich Australian arms manufacturer and big-game hunter, who has become so good at killing animals that he was looking for a new challenge. Due to a newspaper article in which sightings of a huge alligator in the sewers of New York had been reported, he goes to New York City and travels into the sewers. However, Marlin got more than he had expected when he met five intelligent mutant animals instead: Leatherhead and the Turtles.
However, this discovery only increased Marlin's obsession rather than wipe it out. Now, he began hunting the Turtles and Leatherhead repeatedly. In each of his "hunting" tries, he apparently perished, only to reappear and terrorize the mutants again. During a battle with Leatherhead, both his right arm and left foot are lost. Undeterred by his injuries, Marlin replaced the limbs with bionic parts.
Marlin decided on experimenting with the trill of the hunt in a controlled-environment according to his ideas. So, he kidnapped Leatherhead, the Jersey Devil, Mothman, and many other legendary monsters on a remote island off the coast of Australia, which housed one of his weapons factories. The Turtles and Emil Tendaji, a game warden/employee of an organization protecting rare creatures, tracked him and managed to prevent his plan. When the group was attacked by wild monsters, Marlin escaped his captivity to the open sea, only to be eaten by the Loch Ness Monster.
- His obsession with trying to find the next big hunt, makes him similar to the Spider-Man villain "Kraven the Hunter". However, unlike Kraven, he has no problem useing guns.