Demetrius is one of the lovers in William Shakespeare's play A Midsummer Night's Dream.
However, Demetrius merely goes to the forest seeking Hermia, without giving Helena a second thought.
Helena follows Demetrius, and Oberon, the fairy king, sees them arguing.
Oberon feels pity for Helena and decides to help her by putting love juice in Demetrius's eyes, thereby compelling Demetrius to return Helena's love.
Oberon instructs Puck, another fairy, to pour love juice on the eyelids of the "Athenian man".