either the world's most gryffindor slytherin or the world's most slytherin gryffindor. probably a hero or a minor villain of the trickster sort. hero melons are more likely to be that way because of an accident of circumstances or because they identified benefits for them and/or their loved ones than because of any inherent goodness or desire to make the world better, so they're pretty easily swayed by charming villains with good sales pitches.