The Defenders' weren't always a Guild. In fact, (nearly) no one knew each other when our heroes first met. Circumstance and fate brought this group of adventurers together.
It all started in a cave about five years ago. The majority of the crew had been kidnapped from various locations and were being held prisoner by a group of orcish slavers. Ryn Leloup, Rolen Osteroth, Finnileas Sylwynn, Darvin Heartshield, and Basha Alkiniath were face to face with each other, strangers in a strange place [to be fair, Finnileas recognized "Basha" for who she really was (Her Royal Highness, Princess Lunemi Aloyin of the High Elven Kingdom), but he never felt as if he needed to share that].
The party attempted a diplomatic approach to their ordeal with their orcish jailers. When Ryn's attempts at diplomacy faltered, Darvin approached with more of a "heavy-hand." An honorable fight ensued between Darvin and the half-orc jailor, but the half-elven barbarian was bested by his adversary. Regardless, this garnered some respect from the group's captors, and after further negotiations with Rolen (which seemed average at best), the half-orc, Telgar, agrees to try to work something out. There was another prisoner in that group, a dwarf named Donk, and despite the rest of the group wholly unaware of the nearby farming village, it appeared that he knew it well and was able to lead these adventurers right to Centrevale, where the adventurers met Nina.
Much has happened since those early days, but it was those five, along with Donk and Telgar, that then founded the Guild in Centravale; the 'Defenders of the Vale,' with Nina at the helm. Until this point, guilds were a thing of the past. The conclusion of the Great War had not only ushered out the giants and dragons, it disbanded all of the Guilds that had fought against these oppressive foes. Word of a new guild began to leak out, attracting new heroes (and enemies) along the way. Brisingr Fell, Rabijjan, and Basil, the Lesser, were the first recruits to the newly formed Guild, and like the Founders they never disappointed, proving to be overall instrumental to the Guild's future successes.