I am your spaniel, and, Demetrius,
The more you beat me, I will fawn on you.
Use me but as your spaniel—spurn me, strike me,
Neglect me, lose me. Only give me leave,
Unworthy as I am, to follow you. (II.i.)

In Act II, after telling Demetrius about Hermia and Lysander’s plan to run away, Helena follows Demetrius into the forest. We can hear desperation in Helena’s hyperbolic language here. If taken at her word, Helena appears to desire Demetrius so badly that she’s willing to subjugate herself completely, even sacrifice her own well-being. However, Helena could also be deliberately overstating her feelings, using irony to indicate the absurd, dog-like situation she finds herself in.

Run when you will, the story shall be changed.
Apollo flies, and Daphne holds the chase.
The dove pursues the griffin; the mild hind
Makes speed to catch the tiger—bootless speed,
When cowardice pursues and valor flies. (II.i.)

While chasing after Demetrius in Act II, Helena observes that her situation reverses traditional stories of pursuit. Whereas in the stories Apollo chases Daphne, the griffin chases the dove, and the tiger chases the deer (i.e., “hind”), here the hunter has become the hunted. Helena goes so far as to call her situation “a scandal for her sex.” According to her, women “should be wooed and were not made to woo.”

Wherefore was I to this keen mockery born?
When at your hands did I deserve this scorn?
Is ’t not enough, is ’t not enough, young man,
That I did never, no, nor never can,
Deserve a sweet look from Demetrius’ eye,
But you must flout my insufficiency? (II.ii.)

In these lines from Act II, Helena expresses shock and shame after Lysander suddenly proclaims his love to her. At no point has Helena desired Lysander’s affection, and she sees this turn of events as further mockery of her “insufficiency”—that is, her inability to catch “a sweet look from Demetrius’ eye.” Lysander’s sudden amorous pursuit thus has a powerful, negative effect on Helena.

When truth kills truth, O devilish holy fray! (III.ii.)

In Act III Helena uses this dense, punning language to rebuke Lysander for having abandoned Hermia. The basic sense of Helena’s play on words is that Lysander has used the “truth” of his current love for Helena to negate the “truth” of his former love for Hermia. He has therefore acted in ways both “devilish” and “holy”—devilish, because he’s betrayed one vow, and holy, since he’s pledged another one.

Is all the counsel that we two have shared,
The sisters’ vows, the hours that we have spent
When we have chid the hasty-footed time
For parting us? Oh, is all forgot? (III.ii.)

Helena directs these words toward Hermia, who has been a close friend since childhood. Helena’s words here are important, because they signify more than just frustration at feeling mocked and manipulated. Her words also recall how it is primarily women in this play who suffer the consequences of men’s ill-conceived actions. In this particular case, a wedge has been driven in Helena’s friendship with Helena due to the actions of numerous men, including Demetrius, Lysander, Egeus, Theseus, and even Oberon and Puck.