In this excerpt, Grendel is characterized as troubled.
'Troubled' is an adjective used to refer to someone that has problems that make him/her feel concerned and nervous. What indicates that Grendel is troubled is the last sentence ("I was filled with a wordless, obscurely murderous unrest"), especially the use of certain words, such as "wordless" and "unrest", which refer to a disturbed state. Grendel is a novel written by John Gardner and it retells the story of the poem Beowulf from the point of view of Grendel, who is considered a villain in the poem but is presented as a sympathetic character in the novel.
