The characters mentioned in this song are:
Mary: She is pretty, talented and popular, but she gives guys the wrong impression and gets pregnant, possibly with the white guy's baby and it ruins her chances for fame.
White boy: Possibly badly bullied for being a geek. Though he has a lot of knowledge, no one sees that as a good thing. His father is abusing his mother, and one day he cannot take it any more and kills himself.
Greg: Great at basketball, he could be very famous. He has a lot of talent but someone was jealous of him and took his life.
This song gives out a powerful message about how people with a lot of talent really aren't appreciated and eventually will have their lives stolen forever.
lot - birmingam, England