Here is all i know about the covenants lore wise, feel free to add anything or to list your own opinions.
Way of white: i dont know much about them besides the fact that they are clerics from thorolund. and patches hates them.
Sunbros: PRAISE THE SUN
Darkwraiths: this one is rather long. new londo was originally made as an extention to anor londo hence the name new londo.
Gywn saw the four kings to rule new londo, but sadly they fell to dark. how did this happen? and why is new londo flooded. i think the first original darkwraiths were the four kings and thier faithful knights. what is the abyss? the abyss is a pure example of what will happen to the world if the age of fire fades completly and the age of dark comes. Dark stalker kaathe: i belive he is the reason the four kings fell to dark. he tricked them into turning evil and creating the darkwraiths. new londo was flooded by 4 people. The Sealers. one is found dead in blighttown, and one is still in new londo. they flooded new londo so the darkwraiths would forever remain sealed from the world.
Gravelord servants: Nito's tools. what are you doing exactly by "cursing" other people's worlds? you are sentencing them to death so nito can collect them, but the only way you can send a little bit of death into thier world is by opening a rift with an eye of the beast who curses people with thier breath. the baskilisks. yes baskilisks were the original beings that cursed people, but when time began to disort in lordran nito needed a new way to kill people because baskilisks dont exist in time everywhere (technicly they are in everyones game i know) so he used eyes of death. but he knew he couldint curse everyone so he uses undead to do his bidding for him to become stronger as more and more dead souls are collected by nito.
Way of white: i dont know much about them besides the fact that they are clerics from thorolund. and patches hates them.
Sunbros: PRAISE THE SUN
Darkwraiths: this one is rather long. new londo was originally made as an extention to anor londo hence the name new londo.
Gywn saw the four kings to rule new londo, but sadly they fell to dark. how did this happen? and why is new londo flooded. i think the first original darkwraiths were the four kings and thier faithful knights. what is the abyss? the abyss is a pure example of what will happen to the world if the age of fire fades completly and the age of dark comes. Dark stalker kaathe: i belive he is the reason the four kings fell to dark. he tricked them into turning evil and creating the darkwraiths. new londo was flooded by 4 people. The Sealers. one is found dead in blighttown, and one is still in new londo. they flooded new londo so the darkwraiths would forever remain sealed from the world.
Gravelord servants: Nito's tools. what are you doing exactly by "cursing" other people's worlds? you are sentencing them to death so nito can collect them, but the only way you can send a little bit of death into thier world is by opening a rift with an eye of the beast who curses people with thier breath. the baskilisks. yes baskilisks were the original beings that cursed people, but when time began to disort in lordran nito needed a new way to kill people because baskilisks dont exist in time everywhere (technicly they are in everyones game i know) so he used eyes of death. but he knew he couldint curse everyone so he uses undead to do his bidding for him to become stronger as more and more dead souls are collected by nito.