What do Beowulf's battles with Grendel, Grendel's mother, and the dragon have in common?
In all three battles in Beowulf, which include Grendel, Grendel's dam (mother) and the dragon, several elements are present in each.
Beowulf faces seemingly insurmountable adversaries in each battle. Grendel has enormous strength. The first time he attacks the Hall of Hart, he grabs up thirty men and makes off with them, killing and eating them. Grendel's dam has great strength also, but the narrator notes that her power is less than her son's because she is a female. The dragon is able to fly and attack with fire and poison. While Beowulf has clearly proven himself on the battlefield, each of these adversaries is supernatural—beyond the realm of what occurs in the natural world. Suspense is created as he faces each enemy because none of them are human. Regardless of the odds against him, Beowulf is prepared to die bravely if he is not able to defeat these creatures.
Another thing that is present with each battle is that Beowulf fights without equipment that can destroy his enemies, unlike what he usually does. With Grendel, there is a spell on the creature that will not allow metal (swords) to harm him. Even though he is unaware of this, Beowulf decides not to use a sword because Grendel will not be using one—he plans to fight the beast on a level playing field.
...we both, this night,
shall spurn the sword, if he seek me here,
unweaponed, for war
The only reason Beowulf defeats the monster is because his bare hands become his weapons.
When Beowulf attacks Grendel's dam, her blood dissolves the metal of the sword he has carried into battle.
Then sang on her head that seemly blade
its war-song wild. But the warrior found
the light-of-battle was loath to bite,
to harm the heart: its hard edge failed...
An ancient sword he finds in the dam's swampy lair allows him to defeat the creature.
In fighting the dragon, Beowulf's shield and sword fail him, and Wiglaf must come to his aid.
Beowulf shows his bravery in each battle though each enemy exists outside the natural world. Additionally, traditional weapons do not work for Beowulf as they would on an human enemy.
Beowulf does not underestimate his opponents. He acknowledges their strength and prepares himself to face them. He acknowledges Grendel's brute strength, and he gives his best during their battle. Beowulf also decides to carry his shield and sword to face the dragon because he appreciates the beast’s abilities.
In the three battles, Beowulf exhibits superhuman abilities because all his opponents are monsters with supernatural abilities. Beowulf manages to hold on to Grendel and tears off his arm. He fights Grendel’s mother in her underwater lair for hours and manages to wield a sword forged by giants.
In all the battles, Beowulf fights for the people he cares about and for the glory that comes with the challenge. He pursues Grendel for glory and in order to save the Danes. He does the same when Grendel’s mother attacks, and he fights the dragon to protect his people.
Beowulf also conducts himself with the utmost honor in each battle, as do his opponents. Beowulf chooses not to use weapons other than his own hands with Grendel, since this is all Grendel uses. In the battle with Grendel's mother, she brings him to her lair where he is on an equal footing with her--a cave full of air that he can breathe while fighting. He does resort to using the sword forged by giants that he finds in her cave to kill her and to chop off Grendel's head. Both of these battles he fights alone. With the dragon, Beowulf is deserted by all his warriors except for his kinsman, Wiglaf. Again, the honor of a man comes into play. Wiglaf does not forsake Beowulf because he has pledged his life to his King, and also because they are related by blood.
In all of these battles, Beowulf is the stereotypical warrior. He sets out alone, and he relies mostly on his brute strength, as opposed to his wisdom, in order to accomplish his tasks. Consider his battle with Grendel - he holds onto Grendel with a vise-like grip until the monster's arm is ripped from his body. However, Beowulf is compassionate and he is intelligent. He sets out on all of these battles not for glory but to help others, to serve his people. The biggest difference between the battles is in the last one, with the dragon. Here he allows another, Wiglaf, to come to his aid, recognizing that he is too old to take care of the situation himself.