B. <em>Beowulf </em>characterizes Grendel as bloodthirsty, but <em>Grendel </em>shows Grendel's gentler side.
C. <em>Beowulf</em> is sympathetic to the humans, while <em>Grendel</em> shows the monsters perspective.
Explanation:
The strongest point of comparison is that reading both <em>Beowulf</em> and <em>Grendel </em>provides us very different perspectives of the characters themselves.