The references to the wedding of Freawaru and Ingeld are clearly ironic. Beowulf is talking of the dangers of a marriage made to solve a peace. Presumably the audience of Beowulf would have been aware of other stories that we are not aware of and can only glimpse, wherein the events that Beowulf postulates actually happen. From the poem Widsith we know that Hrothgar and Hrothulf (his nephew) were renowned for having defeated Ingeld at Heorot.
Beowulf is therefore being a "prophet" in that he is referring to events that from his POV have not yet happened, but the audience will appreciate the reference to another (lost) poem.
to settle a feud between the two tribes
The poem, Beowulf, is a fictional representation of a historical tale. The story is told by taking events from the past and revamping them as fiction. The tale of Ingeld and Freawaru goes back to the tale of Ingeld and his first wife, the daughter of the Swedish earl, Swerting. The slave who stumbles onto the dragon's hoard is a fictionalisation of the slave, Tunni, who buried the hoard in the ground on the death of his master, and then fought against Egill over the control of it. The name 'Ongen -theow' means 'against-the-servant'. Ongentheow is a character who is equivalent to Egill.The Dragon is Onela. Beowulf is Bothvarr Bjarki. Grendel is Agnar, the child of Ingeld and his first wife (who is the daughter of Swerting). And Grendel's Mother is therefore the daughter of Swerting.The poet appears to have fashioned his story by inserting a couple of episodes (on Grendel and his Mum) into an originally-historical saga on Ingeld, and on Bjarki and Agnar.
Beowulf foresees that the arranged marriage between Hrothgar's daughter and Ingeld will lead to revenge and bloodshed, as it will not effectively resolve the existing conflicts between the two tribes. He predicts that this marriage will not bring lasting peace but rather increase animosity between the two groups.
A Danish king Hroðgar appears in theAnglo-Saxon epics Beowulf and Widsith, and also in Norse sagas, Norse poems, and medieval Danish chronicles. In both Anglo-Saxon and Scandinavian tradition, Hroðgar is a Scylding, the son of Healfdene, the brother of Halga, and the uncle of Hroðulf. Moreover, in both traditions, the mentioned characters were the contemporaries of the Swedish king Eadgils; and both traditions also mention a feud with men named Froda and Ingeld. The consensus view is that Anglo-Saxon and Scandinavian traditions describe the same person.[
grendle is a large (about 15 feet) sickly greenish color made from rotting flesh and he is nude but the layers of scum and mold act as clothing he has a large nose and "pads" for ears that are highly sensitive to sound (that's a reason he killed everbody because people made too much noise) his mouth is demented with rotting teeth. andhe has claws for fingers hope this helps (go to youtube.com a lookup Beowulf 6 min trailer to see what he looks like its the best one to find out)