Lets skip the black magic marker ....i think the best you can do easy is to get a good automotive touch up paint like plastikote clean the spot real good with alcohol or acetone, and either lay a vey small amount of primer and then the paint OR i think you can skip the primer and just put the touch up on it , iv done both, i primer if its bigger then just a small "ding" but to be honest i dont chase after small dings that much.