Answer:
Beowulf's vanity prevents him from noticing when he is being deceived. It was the thing that drove him to fight the horrible beasts. With his hands, he was brought to a dragon, which he was led to his death by. Beowulf, upon entering this room, declared, "That I, alone and with the help of my men, may purge all evil." from this hall (260 & 261). He said "I" and not "us", which shows his true self-egotistical actions, showing his real, selfish nature is shown.