There's 2 options here, read the descriptions first -
Hero -
You get to save people from death, war, pain. You will be well respected, and you will be pretty much law-abiding. You might break some rules along the way, but you don't hurt anyone unless you have to for the greater good. You have a good heart, and hate injustice, and weep over suffering, and you want to end it all.
You can't kill any villains/bad people, unless it's necessary. Your conscience wont let you do it, unless the person was evil and hurting others. Killing a bad person might get the job done quicker, but you don't want to kill anyone, so you will sometimes take the long way around, which sometimes leads to more damage being done by the bad guys, but you don't think it's right to kill someone simply because it could be easier and less risky. Saving lives and seeing criminals face proper justice is what you want, which is why you are loved by most.
You can have a loving family, and your child(ren) will become hero's too, so they can look after people when you grow old and unable to fight anymore. You wont live much longer than the average human since you fought completely for others. There's dark energy out there that could prolong your life, and maybe even make you stronger and a more effective fighter, but bad things can come from it. It can twist you, and lead you to perish.
You'll die peacefully, knowing that the world is under the care of more heroes. You might wish you did more things for yourself sometimes, and wonder if casualties could have been avoided if you had embraced the darker side, and had the power to crush evil more efficiently. But you're glad you fought selflessly, and did the right thing, and have peace of mind because of this.
Anti-Hero -
You are bad in many ways. You break legs to get information. You wont hesitate to kill if it gets the job done, even if lives could sometimes have been spared, and criminals could have faced justice behind bars. You don't care if they were perhaps a good person underneath, they were doing bad stuff and firing at you, so they are gonna die. Innocent people have been saved, justice has been served, bad guys are dead.
You take your share of the goods before handing the criminals over to the authorities. You aint working for free, are you? You get to take your share of cash, drugs, cars, dark energy from villains to become more powerful etc.
You will likely not end up falling in love, but you get to have a lot of great sex with the freakish sexy people who you make wet/hard. Thus you might have a bastard child with one of the people you banged. There's an equals chance that he/she will become a Hero/Villain. You will live longer because you chose to fight for yourself, and embrace the dark energy which made you stronger.
Thus you might have been able to defeat evil more efficiently than the heroes, and sometimes saved even more lives.. But despite your longer and more pleasurable/self indulgent life, you will likely get tired of your existence and go out with a painful bang, but a bang that will see you fight one last time to save people. You will let out a might battle roar full of conflicting emotion. You are proud and fulfilled in a way because you saved lives with your final act, but wishing you could have been a better parent to your child that you aren't sure will fight for good or not.
You could have spawned the next Hero or Villain. You have defeated evil more efficiently, perhaps stopped a significantly terrible event that could have lead to evil reigning, but only in this chapter...
