Osiris was part of the team due to the armour: Tread of the Hezen Lords. Toland** was part of the fireteam that went with Eris to the moon and to find Crota. Kabr was consumed by the vault itself but he created the relics to leave a remnant of himself and for any other guardian who dared to enter the vault again to defend themselves. Now Praedyth is the odd one in the group because we learn about what really happened to him or what the vanguard has speculated even though we hear his voice and he says he lived. "His fall has not happened yet, and will happen again." Is it madness? Im not entirely sure. Pahanian is the one who constructed SGA and witnessed Kabr fall, so perhaps he is going to go mad? You can find any sort of lore you need on Reddit or directly message some like Anonpig who knows just about everything. I tried my best there! Hope it helped you