In Act 1, Scene 1, Helena runs into Hermia and Lysander, who have just vowed to run away together. Because Helena and Hermia are friends, Helena is able to express her anguish over Demetrius. She uses a metaphor to praise her friend and to demonstrate how beautiful she must seem to Demetrius. Her speech is full of jealousy, since she wants to be more like Hermia and hopes to win Demetrius over. She describes her friend this way:
Your eyes are lodestars and your tongue’s sweet air
More tunable than lark to shepherd’s ear
When wheat is green, when hawthorn buds appear.
Helena compares Hermia’s eyes to lodestars, the stars that seamen use to guide their ships. The metaphor implies that Demetrius looks to Hermia’s eyes for direction and guidance and that he follows them faithfully in order to keep his life’s course. Hermia’s voice, according to Helena, is perfectly fit for Demetrius’s ear, as it is like a bird in springtime. She uses these metaphors to paint a picture of what she imagines Demetrius’s love does to Hermia, making her eyes and voice the pillars of his existence in the world. Helena’s desire is clear in these passages: she wants Demetrius to feel this way about her instead of her friend. But her descriptive language also reveals how Helena imagines love, and her speech is therefore also an expression of her loving anguish over Demetrius. She is able to see how he loves Hermia because she has the same watchful eye of the unrequited lover.
The central conflict between Oberon and Titania is over the custody of a "changeling" child from India. In one of their initial arguments over the boy, Titania uses a metaphor to imply that she is better fit to parent than Oberon. She recalls the story of her acquaintance with the boy’s mother, saying:
When we have laughed to see the sails conceive
And grow big-bellied with the wanton wind;
Which she, with pretty and with swimming gait,
Following (her womb then rich with my young squire),
Would imitate and sail upon the land
To fetch me trifles and return again
As from a voyage, rich with merchandise.
In this passage, Titania describes the relationship that she had with the mother, whose eventual death left the boy parentless. Titania's story of their time together in India is punctuated by a metaphor of sails and laden with the language of pregnancy and conception. The ships in her story are swollen as though with child, as her young attendant was. Titania uses this metaphor to remind Oberon that she is capable of motherhood and that her body has a connection to the process of childbirth, even though the child is not her biological son. In the tussle of power between Oberon and Titania, she uses descriptive language to gain the upper ground. She wants Oberon to understand that her attendant would have wanted her to have the child because of their shared experience—that is, because of the jokes they made about the motherly shape of the ships that passed them when they sat together. She seems to imply even that the boy is a gift, first to the mother, and then to Titania after her death.
In Act 3, Scene 2, Lysander uses a simile in a tirade against his former lover. He has been bewitched by a love potion and has thus abandoned Hermia for her friend. His change of affection is shocking, as it is magically induced, and when he and Hermia are reunited, he uses figurative language to communicate the extent of his disinterest. He is trying to discourage Hermia; he wants to get rid of her in order to return to his single-minded pursuit of Helena. His speech is in response to Hermia touching him. When she takes his arm, he says:
Hang off, thou cat, thou burr! Vile thing, let loose,
Or I will shake thee from me like a serpent.
In this section, Lysander uses a simile to compare Hermia to a serpent. But before he does that, he metaphorically calls her a cat and a "burr," implying that she's clinging to him (much like the prickly seeds known as "burrs," which often stick to people). He employs this language in an attempt to discourage her. In his speech, he compares her to a series of things that are tiresome in clinging to him, therefore communicating how desperately he wants her to let go of him.
The simile comparing Hermia to a serpent, though, is the most meaningful. Lysander says that he will force her to release him the way he would get rid of a serpent. His comparison to a serpent in this moment is very significant because Hermia woke up from a nightmare about a serpent as he left her sleeping side. In her nightmare, a serpent ate her heart while Lysander watched. His unknowing reference to her nightmare casts her as the serpent, implying that she is the source of poison and that, in this case, he will not hesitate to get rid of her. This statement charts as especially cruel, as Hermia’s waking wish was for Lysander’s protection from her own nightmarish serpent.