Through Grendel's own hatred and anger, he brings his own downfall. The "sin-stained demon" has his roots in the vile creature Cain. Since Grendel is spawned from Cain, he can never feel the love of God or of people: ". . . God, / Whose love Grendel could not know." (84-85). It is because of this, that Grendel hates every mortal being he lays his eyes upon. Hatred leads to anger, constant anger, ". . . bearing God's hatred, / Grendel came, hoping to kill" (393-394). Fear is Grendel's other major flaw, "His mind was flooded with fear . . ." (435). Through his hatred and fear, Grendel seals his own fate.
Anger then yields itself to insecurity and low self-esteem. The moment Grendel realizes that there is someone just as strong as him, he tries to run away, ". . . Grendel's one thought was to run / From Beowulf, flee back to his marsh and hide there:" (437-438), but it is too late. Just like when the average bully meets his match, he runs in fear of not being able to win. Grendel does not have the audacity to stand up to Beowulf with all his might and therefore falls to Beowulf.
The exact opposite of the points mentioned thus far are made manifest within the character of Beowulf. Beowulf is easily able to defeat Grendel once Grendel has lost all hope of winning, ". . . remembered his final / Boast and, standing erect,