The play takes place in ancient Athens, Greece. In this play, fairies tinker with mortal lives and have to fix the trouble they have caused. Through the characters of Oberon, Titania, and Robin, Shakespeare shows the negative consequences imparted onto mortal lives that can result when immortal fairy creatures possess strong human emotions.

The first human emotion these fairy creatures possess is jealousy. Oberon and Titania are characterized with this emotion. A good example of them showing this emotion is when Oberon fights with Titania over the Indian boy. "Give me that boy and I will go with thee." (Shakespeare 2.1.148). Oberon is showing jealousy here because he is jealous of Titania for having her own Indian boy as a slave. This negatively affects mortal lives by causing the weather to drastically change for the worse.
Another example of them showing jealousy is when Oberon accuses Titania of loving Theseus after she has accused him of loving Hippolyta. "How canst thou thus for shame, Titania,/ Glance at my credit with Hippolyta,/ Knowing I know thy love to Theseus?" (Shakespeare 2.1.76-78). Oberon and Titania fighting about who loves who shows jealousy exquisitely well because it shows Oberon and Titania's insecurity with their own relationship and how they can not trust each other. All in all, Oberon and Titania show the human emotion of jealously very well.
The second emotion shown by fairies is compassion. Oberon is characterized as displaying this emotion. He shows this emotion when he tells Robin to help Helena with her love issues. "A sweet Athenian lady is in love/ With a disdainful youth. Anoint his eyes,/ But do it when the next thing he espies/ May be the lady." (Shakespeare 2.2.268-71). This shows Oberon's compassion because he feels sorry for Helena's trouble with men and wants to help her. This has a negative consequence on mortal lives because Robin anoints the wrong Athenian's eyes and creates a big love problem. All in all, Oberon shows the human emotion of compassion very well.
The last human emotion shown by the fairies is mischievousness. Robin is characterized showing this emotion. Robin shows this emotion when he turns Bottom's head into that of an ass. "What do you see? You see an ass-head of your/ own do you?" (Shakespeare 3.1.128-9). This shows Robin's mischievous nature because he mischievously turns Bottom's head into an ass-head. This has a negative effect on mortal lives because now bottom has an ass-head. All in all, Bottom shows the human emotion of mischievousness very well.
In conclusion, one can conclusively conclude that negative consequences are imparted on mortal lives when immortal beings possess strong human emotions. Shakespeare ingeniously characterizes the fairy characters with these characteristics to characteristically show how fairies affect mortal lives in everyday life. If this seems redundant, you should read A Midsummer Night's Dream by William Shakespeare.