In Chapter 1, Grendel wanders around the countryside in a beautiful Danish spring, bemoaning that he is a "pointless, ridiculous monster." He is frustrated with nature, which seems indifferent to his suffering. But just as Grendel's fit of sadness reaches its peak, he reveals that he was exaggerating sarcastically. This verbal irony is a prime example of how the monster is often an unreliable narrator:
“Ah, sad one, poor old freak!” I cry, and hug myself, and laugh, letting out salt tears, he he! till I fall down gasping and sobbing. (It’s mostly fake.) The sun spins mindlessly overhead, the shadows lengthen and shorten as if by plan. Small birds, with a high-pitched yelp, lay eggs. The tender grasses peek up, innocent yellow, through the ground: the children of the dead.
Grendel watches the passage of the sun, birds laying eggs, and new grasses growing out of the soil: all three of these are examples of the endless cycles of nature, whether the passage of days or of life and death. Grendel cries out against them, because he, the "poor old freak," disrupts those natural cycles with his murderous ways.
But Grendel's brief aside complicates the passage. He confides in the reader that his gasping and sobbing is "mostly fake." It seems Grendel melodramatically plays up his emotions for effect. The reader assumes that, just as Grendel's tears are fake, so too are his words about the cycles of nature. Grendel does not say what he really means, resulting in verbal irony.
What are Grendel's real feelings in this moment, if his tears are "mostly fake"? In the novel Grendel regularly embellishes the story to cast himself as a tragic, embattled antihero. But here he briefly lets on that some of his pained emotional episodes are not truthful. Grendel's first-person narration manipulates his own story, making him an unreliable narrator. In the original Beowulf poem, Grendel is usually described as being cloaked in a cloud of shadow: it is impossible to see him clearly. In Grendel, the monster is just as difficult to perceive clearly because of his own desire to tell his story favorably.