In the passage describing Grendel in the epic poem Beowulf, Grendel is characterized primarily as fearful, sickly, and troubled rather than peaceful. During the fight with Beowulf, Grendel experiences intense fear and pain as Beowulf's strength completely overwhelms him. He shrieks in pain and terror like a cornered animal and longs to retreat to the safety of his swampy home. The passage also portrays Grendel as a mysterious, evil, and monstrous creature cursed by God, linked to biblical Cain, living as an outcast and embodying evil and malice. His twisted, grotesque form and his pain and wounds during the battle add to the image of a sickly and troubled being haunted by his curse and loneliness. Consequently, peaceful is not an accurate characterization of Grendel in this context. Summary of Grendel's characterization in the passage:

• Fearful and terrified during the battle with Beowulf
• Sickly or wounded as Beowulf fatally injures him
• Troubled by his cursed, outcast existence and malice
• Not peaceful, but a violent, evil monster embodying darkness and pain.

Therefore, Grendel is best characterized as fearful, sickly, and troubled in this passage.