365 Tomorrows has a short story every day about the future, I recently started to read it and this is one I really like.
Pluto Immortal: "Marcus wiped blood from his chin. The thick red fluid stuck to his fingers. He stood slowly, pushing himself up off the ground with all the dignity he could muster as his foe stood proud and arrogant. Marcus’ feet were pressed into the soft Mars soil as he readied himself again. “You fool!” Marcus screamed out across the yards between him and his adversary. “You do not comprehend how much more precious is my life than yours! I am Mars-born!” Gaither kept his eyes on his quarry and turned his attention inward for a moment. Focus the rage. Do this professionally. It’s a high-profile case; lots of media attention. Don’t give them any reason to cry brutality. His fist ached from cracking into the Red Planet monster’s jaw. He shook it off and pushed the pain back down, eyes boiling with a deluvian hatred that conquered all other emotion. He knew that if he didn’t kill him today, Marcus would go on living for another four hundred years. All of the Mars-born did- at least the ones who could escape Marcus’ knife. This time, however, Gaither had to stop him. Ninety-seven murders, eighteen rapes, and so many robberies that NASA police were still piecing it all together; Marcus had outdone every other criminal in extra-Earth territory. It stopped here. The fiend spat blood, shaking off the solid hit that ja"