Major Story Arc
The Future Shark Trilogy
One day when the Teenage Mutant Ninja Turtles were relaxing in their lair, a mysterious portal opened and out of it came two other mutant turtles who claimed to be Donatello and Raphael from a distant future. The two had come back in time seeking the help of their past selves after the future versions of Leonardo and Michaelangelo had been captured by Shredder, Verminator-X, and Armaggon. The TMNT chose to help their future doppelgangers and went to the future where they were shocked to learn not only did they live in the public, but were incredibly wealthy as well thanks to Donatello's numerous inventions, mostly his re-design of Baxter Stockman's Mouser robot. The six turtles and Ninjara fought the trio of villains and their unexpected ally the Rat King and freed the future versions of Leo and Mike, along with Merdude who had been captured by Armaggon unbeknown to any involved.
Future Donatello and Raphael were later seen helping the Mutanimals build their new base of operations, but between returning to the future and coming back to the past, the Mutanimals were killed by the Gang of Four. Slash arriving on the Mutanimals island after hearing the gunfire assumed that the Future TMNT were the killers and a battle ensued between the three turtles. After the FTMNT cleared things up with Slash, the three sought the help of the TMNT, and confronted Null, Maligna and their thugs. In the aftermath Slash lost his life, an event Future Donatello said never should have happened, and that in their time line Slash and the Mutanimals were still alive. It was then that the Future Donatello realized that the Time Slip Generator had not taken him back to his past, but the past of a completely different reality, one he had no business interfering in.