Shapeshifter

A doctor was trialing a cure for the common cold.

It was explained to you that the cold virus constantly mutates so by the time a doctor has made a cure it is no longer effective.

So you needed a cure that also mutates.

After the cure had got rid of the cold it infected your cells and after a while you started to mutate.

You learned to control it after a while and you now can make yourself look like anybody you want.

You can even change the collour of your hair.

What made you become evil?