Final answer:
When Grendel arrives at the mead-hall, the Danes are enjoying their nightly celebrations, which include feasting and storytelling. Mead-halls were important cultural and political centers in Viking society. Grendel's invasion brings a dramatic shift from celebration to terror and struggle.
Step-by-step explanation:
When Grendel arrives at the mead-hall in the epic of Beowulf, the Danes are often depicted as partaking in their nightly festivities which include feasting, drinking, and the sharing of stories and songs. Mead-halls, like these, were central to the social and political life of the Vikings. These halls were places of community gathering, symbolizing wealth and power, where leaders and warriors would convene, celebrate their victories, and plan future endeavors.
The arrival of Grendel, the monster in the narrative, typically marks a turn from jovial revelry to horror as he attacks the hall, threatening the lives of those inside and putting an end to their peace and prosperity. The mead-hall under the threat of Grendel becomes a recurring theme of conflict and a symbol of the struggle between good, as represented by the Danes and their hero Beowulf, and evil, symbolized by Grendel.