What function does unferth serve in the poem On Beowulf?

In the poem Beowulf, Unferth plays a significant role as a foil to the protagonist, Beowulf. He challenges Beowulf's reputation, bravery, and swimming prowess, thereby setting the stage for Beowulf's subsequent triumphs and heroic feats. Unferth's skepticism prompts Beowulf to recount his epic encounter with the water demon Grendel's mother. Through this interaction with Unferth, Beowulf emerges as a true hero with extraordinary abilities and courage. Additionally, Unferth contributes to the development of conflict and tension within the poem, which propels the narrative forward.