The Fairy Queen and King have an argument; Helena chases Demetrius into the woods.
Characters: 
Fairy

The Fairy serves the Fairy Queen Titania, and learns from Robin about the discord between Titania and the Fairy King Oberon. 

Robin (Puck)

A mischievous hobgoblin, Robin (also known as Puck) is tasked by Oberon with finding a magical flower whose nectar can make a person fall in love. 

Titania

The queen of the fairies won’t give Oberon one of her attendants, a changeling boy, and complains to Oberon about the impact of their argument on the natural world. 

Oberon

The king of the fairies, Oberon wants Titania to hand over one of her attendants, a changeling boy, so he concocts a plan to trick Titania into falling in love with a beast. 

Demetrius

In an attempt to catch up with Hermia and Lysander, Demetrius has entered the wood, where he is pursued by Helena, who is in love with him. 

Helena

In love with Demetrius, Helena has pursued him into the woods, and refuses to leave him alone. 

Scene Summary: 

A Fairy and Robin Goodfellow (Puck) discuss Titania, the Fairy Queen, and Oberon, the Fairy King. Oberon wants Titania to give up one of her attendants, a changeling boy, so that he can join Oberon’s entourage. When Titania and Oberon arrive, they immediately begin to argue over the boy. Titania reminds Oberon that Athens has been suffering from natural disasters because of their discord, and Oberon points out that Titania could bring it all to an end by giving him the boy. Titania leaves to avoid an actual fight. As soon as she’s gone, Oberon plots revenge. He tells Puck to search for a flower whose juice can make a person fall in love with whatever they see next. He plans to use the flower on Titania.

Just then, Demetrius and Helena arrive in the wood, so Oberon makes himself invisible and eavesdrops on their conversation. Helena is following Demetrius, who wants nothing to do with her. When Puck reappears with some of the flowers, Oberon reminds us of his plan to use the love potion on Titania. Then he tells Puck to find the Athenian couple he just saw and to put some of the love potion in the Athenian man’s eyes so that he falls in love with the woman. Oberon and Puck go their separate ways.