sight of men.

Of Cain awoke all that woful breed,

Etins and elves and evil-spirits,

as well as the giants that warred with God

weary while: but their wage was paid them!

There came unhidden tidings true to the tribes of men, in sorrowful songs, how ceaselessly Grendel harassed Hrothgar, what hate he bore him, what murder and massacre, many a year, feud unfading, — refused consent to deal with any of Daneland’s earls, make pact of peace, or compound for gold: still less did the wise men ween to get great fee for the feud from his fiendish hands.

Never to any man erst I trusted, since I could heave up hand and shield, this noble Dane-Hall, till now to thee. Have now and hold this house unpeered; remember thy glory; thy might declare; watch for the foe! No wish shall fail thee if thou bidest the battle with bold-won life.

Beowulf is one of the oldest surviving epic poems in the Old English language. The manuscript was produced between 975 and 1025, but we do not know when the actual poem was first composed. We also do not know who the original poet was; that mystery person is referred to as the “Beowulf poet.”

In this epic poem, the great hero Beowulf comes to the aid of the tormented Danes. He slays the monster Grendel and then Grendel's monster mother, and eventually kills a dragon. He dies in the final battle with the dragon, but successfully rids the land of its plague of monsters.

One of the requirements for “heroes” in ancient English literature is an inherent imperative duty to help those who are helpless and in danger. Beowulf fulfills this role. Beowulf has no obligation legally to help the Danes. He actually serves a different king and is a hero of the Geats. He is not part of the Scandinavian tribe being attacked by Grendel, a monster descended from Cain. Thus, Beowulf asks his king if he can go to the aid of the Danes and King Hrothgar, and his king allows it. Beowulf leaves his land to go assist people he has no obligation to, and that action makes him a hero. So, even though Beowulf does not know Hrothgar well, he decides to come to his aid and help rid the great hall Heorot of the monster Grendel.

Although not related by blood, Beowulf the Geat shares a name with a beloved Danish king of old. Hrothgar knew Beowulf's father, and so the two had a respectful allegiance to each other. Hrothgar had interceded on the Geats behalf years before and prevented a war, so both Beowulf and Hrothgar saw Beowulf's coming as a valorous and honorable deed.

Even though Unferth questioned Beowulf's abilities, Beowulf's account of his own victories over sea monsters was sufficient for Hrothgar to see the heroic ideal working itself out in Beowulf and brought him in as a friend and son of the Danes.

Hrothgar is the King.  His people are "retained" through loyalty and love.  In Anglo-Saxon times, loyalty and family ties meant everything.  Hence, Grendel is such a monster mainly because he is descended of Cain, who murdered his own brother.  Crimes against family, blood, and loyalty oaths were considered unforgiveable.

So, anyone fighting to protect Hrothgar would have received the pledge that the King would take care of him as Hrothgar expected the warrior to protect the King.  As payment for a warrior's loyalty, Hrothgar often gave rings or other trinkets of wealth.  This is how the kings of the time period came to be known as "the ring-givers".   The bond can only be honorably broken through death.