Norse clans had a strong belief in ancestor worship, as well as the rest of the Nordic pagan pantheon. An important part of clan histories was the mythos that described the creation of the bloodline - usually this stemmed from an individual or entity who was responsible for great acts of heroism or mighty deeds. The clan would then be named for that person. In this case, the Brunder were named after an ancestor of the same name (although by common naming conventions, I'm not sure if we should be the 'Brunderlings'?). Basically, we need to work out what mighty deeds Brunder can lay his name to. It's a given that over the generations the tales become taller and more exaggerated, incorporating supernatural, magical and spiritual elements. It's par the norm to end up with a Berserker type bloke who arm wrestled Odin, when in actuality he was just a farmer who chased off a shifty looking traveler once upon a time. I'd also like to work in the idea of a 'patron' animal here, as a sort of spirit guide that members have adopted. Here's my proposal: Myth: Brunder is found as a baby in the woods at the base of an oak tree that has been split in half by a lightening strike. He is found by a gyđja (priestess) of Gefjon who is on her way to a vé (sacred enclosure/clearing) of the gods. She takes the infant in, proclaiming that he is blessed by Thor, the lord of lightning. Brunder grows to be of mighty size and a great warrior. Raised by the priestess, he vows to fight evil in the name of Odin and Thor. He leaves the priestesses' home to travel north, towards the islands of the Gods and looking for worthy causes. On crossing the Limfjord onto the North Jutlandic Island, he hears a tale of a terrible beast that has been ravaging the northern regions. It is the monstrous giant Agajótr (ugly terror), a son of Loki. He vows that he will slay the giant, and sets off to find it. After a long period of searching, he comes across the giant itself. Two times he fights it. The giant is too tall and fierce for him to effectively wound, so he retreats defeated to consider his options.While resting in a nearby grove, the goddess Gefjon takes pity on him and sends a spirit form that has taken the shape of a badger. Gefjon is the god of Zealand, and has no desire to see its people terrorized by the offspring of Loki, a god who has gravely insulted her in the past. The badger, as a creature representing counsel and wisdom, offers to descend down its tunnels into Svartálfaheimr, the underground realm of the dwarfs and find the brothers Brokkr and Eitri. The brothers have previously fallen foul of Loki, who tricked them out of his head after losing a bet. They relish the chance to strike back at his kin, agreeing to forge a weapon in return for the giant's head. To defeat the massive giant, the brothers create a great halberd from Brunder's sword, naming it Jötunnbítr (Giant-Biter).Brunder returns to the giant for a third time, now with Jötunnbítr. He lops the creature's head off after a long fight. As agreed, the dwarf brothers claim its head to satisfy their revenge. Brunder thanks the badger for its assistance, and pledges that its kind will be honoured by his descendants for as long as his line continues. The people of the region greatly celebrate his deeds as a hero, and build a great longhouse at the site of the fight in his honour. As the giant's head has been taken, several of its leg bones are used for the doorframe as a memorial to the victory. A settlement grows around the longhouse, eventually becoming Brřnderslev and the founding homelands of Clan Brunder(ling?).
Maybe he wrestled the giant to the ground, but his sword shattered as he tried to behead it, then the badger came. It just seems like he should have some manly feat of unarmed combat