Symbolism, Imagery, Allegory
This isn't so much a symbol as a sticky, brown mess stuck onto Paul Marshall. Because Paul Marshall is the kind of guy who should be festooned with sticky brown messes.
Paul makes his fortune from chocolate, of course. Or, more specifically, he makes his fortune selling chocolate to soldiers. The "Amo Bar" is a pun. It sounds like "Ammo," or bullets. But it also references the Latin word for love—presumably because the chocolate will remind soldiers of home. Paul sells chocolate named for love and death—which seems appropriate, considering the fact that he's a rapist.