I am rather a sick fuck in this department, and i think about it alot actually. Not that I will ever do these things, but they are fun to think about....
So as a serial killer, I would be a child torturer and murderer, mostly boys ages 0-9. white. I'd kidnap them from parks/homes/wherever and keep them in a custom, secret dungeon. They would never leave and would be kept alivre as long as physically possibly, while withstanding the worst tortures I could come up with. I would always be in a full rubber suit- hooded/masked and gloved so they never see my human characteristics at all. I would become known as (something along these lines) the rubber boy snatcher, rubber killer, toddler killer, etc etc. Id never get caught and i would keep leading an unassuming life, while I have a constant stream of tortured young boys and even infants in my basement :)