Here's a breakdown:
* The nature of good and evil: Grendel constantly questions the labels humans impose on him. He doesn't understand why they consider him evil simply for being different and acting on his instincts. He struggles to reconcile his actions with the idea of good and evil, wondering if he's truly monstrous or simply misunderstood.
* The purpose of life: Throughout the novel, Grendel contemplates the point of his existence. He witnesses the rituals and beliefs of humans, questioning their motivations and finding little meaning in their actions. He yearns for a purpose beyond simply surviving, but struggles to find it.
* The nature of consciousness: Grendel is a creature of immense intellect, capable of deep thought and reflection. He is aware of his own mortality and the passing of time, leading him to question the nature of consciousness and the value of his own existence.
* The meaning of language: Grendel is fascinated by human language and its power to shape reality. He observes how humans use language to create meaning, but struggles to understand and use it himself. His inability to truly communicate with humans adds to his feeling of isolation and alienation.
* The role of fate and free will: Grendel is constantly aware of the forces that seem to control his life. He grapples with the idea of free will and whether his actions are truly his own or determined by fate. This conflict contributes to his sense of powerlessness and ultimately fuels his destructive impulses.
In essence, Grendel's existential crisis is a search for meaning in a universe that seems indifferent to his existence. He grapples with fundamental questions about good and evil, purpose, consciousness, language, and the nature of reality itself, ultimately searching for a place where he can find meaning and connection in a world that seems to reject him.