Foreshadowing in Beowulf
For the purposes of the story, it is important that Grendel's reign of terror lasts as long as it does. By stating that the dire situation became well-known among the Danes, Swedes, and Geats, the poet foreshadows the coming of a hero to save Hrothgar's Hall.
The digression here to the story of Sigemund serves several purposes. First, by linking Beowulf to the cultural hero Sigemond, Beowulf is praised and his reputation is greatly enhanced. Second, the inclusion of this tale is meant to foreshadow more conflict in Beowulf's life.
The poet links Beowulf with the the legendary hero Sigemund, from a series of tales from the Old Norse Volsunga Saga that an Anglo-Saxon audience would know. The effect is to build on an existing narrative and perhaps foreshadow coming events in Beowulf's own story.
The poet foreshadows dynastic problems that are yet to come for Hrothgar's Danes. The mention of Hrothulf, Hrothgar's nephew, may support the belief of some scholars that the foreshadowed treachery involves both Unferth and Hrothulf against Hrothgar.
Unferth may be Hrothgar's orator, but he is also an untrustworthy man who has killed his own brothers. By mentioning that Unferth sits in a prominent place in Hrothgar's hall, the poet is likely foreshadowing that all is not well and informing the audience of future discord.
The poet's choice of using Fate and cruel destiny in this passage foreshadows conflict that will shortly come to Hrothgar's hall. Interestingly, this choice omit's reference to the Christian God, preferring to use the pagan concept that controls mankind.
The poet uses the concept of fate to foreshadow the death of one of the warriors at the feast. For those living during Beowulf's time, when a man is fated to die, he will die, and there is no action the doomed man can take that will alter his fate.