Hrolf is mentioned in Beowulf as Hrothulf. It is not said which of Hrothgar's brothers is his father, but later tradition makes it Halga (instead of Heorogar), because the Saga does talk about his relationship with Halga. The "kraki" that gets tacked onto his name means "tall, angular, slender" and no doubt referred to his physical appearance.
The Saga was composed in Iceland about 1400, and brings together many separate incidents in history and legend, tied together by their connections to Hrolf Kraki and the members of his family, including his father, aunt, and uncle. Its five sections each focus on a different set of people. The first section of four chapters presents a long and illustrious lineage for Hrolf and the struggle for control of the Danish kingdom.
Chapters five through 13 deal with Hrolf's problematic father, a man of uncontrollable ... appetites. He cannot resist women, and apparently doesn't want to: he ignores any advice about caution. This leads him ultimately to a liaison with Yrsa, by whom he sires Hrolf. This is followed by a few chapters about some men who will later become champions in King Hrolf's service.
What follows next is the tale of the bearlike Bothvar Bjarki, in many ways a completely separate story that was grafted onto the Saga by its link to Bothvar working for Hrolf. It is an elaborate tale of magic and adventure far more complex than the summary I gave in the previous post. I've previously discussed some of the shared elements between his story and Beowulf's.
The final ten chapters are more directly about Hrolf himself. Prior to this the Saga has introduced all the significant characters surrounding him, not just warriors but also several notable women. Women make up a large part of these sections: men seek their advice, there is an elfin woman and her daughter who change the destiny of anyone who encounters them, details of marriages (both good and bad) are revealed.
In fact, although Hrolf is of course the focal point for the Saga, women are frequently the connective tissue between different episodes. One in particular is his mother, Yrsa, whose tale is fascinating and deserves to be known. See you next time.