I recall a Marvel/DC crossover game I ran for a long time using the Marvel Supers rules. At one point, Deathstroke used the soft-space gate the PC's had set up a facility around, and snuck through while the players were elsewhere. He then raided the X-Mansion's computer system for information on who his counterpart in their reality was.
After chugging away for a few minutes, Cerebro eventually spat out a genetic match: Craig Hollis, also known as Mr. Immortal. He's got the same power Deathstroke has: He can't die. But unlike Deathstroke, who turned it into an advantage in his line of work, Mr. Immortal is always trying to find new and more creative ways to kill himself. He's only a hero by accident, as a rule, and couldn't be bothered to try harder.
In the game, after discovering what his alternate was like, Deathstroke very deliberately erased all evidence of his own tampering, returned to his reality, and refused to even discuss the other reality ever again.
Of course, that's also the game where the PC's discovered Cadmus had raided across the boundary and obtained a sample of Mystique's DNA. They combined it to create another DNAlien. This one was based on a combination of Mystique, Superman, and the Venom symbiote. "Mystaque", as the players called her, was another uncontrollable monstrosity Cadmus was responsible for unleashing on the game universe...
---
Those who fear the darkness have never seen what the light can do.
After chugging away for a few minutes, Cerebro eventually spat out a genetic match: Craig Hollis, also known as Mr. Immortal. He's got the same power Deathstroke has: He can't die. But unlike Deathstroke, who turned it into an advantage in his line of work, Mr. Immortal is always trying to find new and more creative ways to kill himself. He's only a hero by accident, as a rule, and couldn't be bothered to try harder.
In the game, after discovering what his alternate was like, Deathstroke very deliberately erased all evidence of his own tampering, returned to his reality, and refused to even discuss the other reality ever again.
Of course, that's also the game where the PC's discovered Cadmus had raided across the boundary and obtained a sample of Mystique's DNA. They combined it to create another DNAlien. This one was based on a combination of Mystique, Superman, and the Venom symbiote. "Mystaque", as the players called her, was another uncontrollable monstrosity Cadmus was responsible for unleashing on the game universe...
---
Those who fear the darkness have never seen what the light can do.