The supernatural is explained as something that is above or beyond what is natural and is generally associated with magic or divine power. In A Midsummer Night's Dream the supernatural is magic in and from a fairy world that is connected with our world through dreams.
When discussing the role that the supernatural takes in the play it could be argued that those characters who are above and beyond the natural world use that power to manipulate others. Oberon uses his magic to manipulate Titania into giving him the little boy. Consequently, Puck messes with poor Bottom and changes his head into that of a donkey's in order to do Oberon's bidding to manipulate Titania. Also, Puck makes mistakes with the young lovers when trying to execute Oberon's commands and winds up causing more trouble and confusion which add to the play's comedy.
Clearly, Titania, Bottom, Lysander, Demetrius, and Hermia all get manipulated because of Oberon's and Puck's ability to use magic on others; and, this seems to be one way to look at the role of the supernatural in the play-- as a manipulating device. :)
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