As in From, added covenants to Demon's souls like this (please keep in mind this is a hypothetical thread for discussion. I don't actually expect this to happen I just think its a fun idea. If you don't agree with redoing demon's souls please don't post on here as this is for fun, not serious.):
There would be 5 covenants in the game (1 for each world) that you could join at some point in the level.
Boletaria's covenant. Members are given a stone and invade people who have sinned by killing an npc or the old king. The covenant is joined by talking to the old king. Upon joining players are given a unique sword (not the demonbrandt) and the stone. They rank up in the covenant by killing players through invasion. Through ranking up the player gets a special armor and eventually gets a special sword that steals the essence of demons when they are struck. You gain 1% of your enemies souls when they are struck with it, but if you die while invading you lose all gained souls. In this covenant you can invade regardless of our form (human/hollow/spirit) but the victim loses no humanity or their body, only souls.
Stonefang tunnels covenant. This is a pyromancy based covenant taken by talking to an npc added before the Dragon God fight. Through this covenant you are given a better pyrmancy catalyst and a Red Soapstone allowing you to request duels. You rank up by beating people at duels and only people within the covenant can request duels. As you rank up you obtain unique pyromancies. The first being dragon's breath and the second being dragon's skin. The breath allows you to breath fire at a low mp cost, the second raises your physical defence and stamina regeneration. Finally you obtain dragon's body turning you into a dragon. Your damage and defence are slightly boosted. Your stamina regeneration is also boosted. However you cannot wear armor when using the spell.
Tower or Latria covenant. This covenant is joined after defeating the old monk. A servant of his hails you as the new old monk. You get a special invasion stone that allows you to invade worlds that have are already being invaded. You and the invader can do damage to eachother, but you do not leave until you kill the host. As you rank up you aquire new spells until you reach the highest rank you aquire a catalyst that allows you to cast any kind of magic.
Valley of Defilement covenant. This covenant is joined by sparing maiden astrea during the boss fight. She gives you her soul in return for your service to her. The covenant is a miracle based covenant. When you join you get the silver catalyst and a stone that allows you to draw invaders to your world. As you rank up you acquire better miracles until you reach the final rank you are given a special armor set that resists damage from dark spirits.
The Shrine of Storms covenant. This covenant is joined by resurrecting a body in one of the graves in the final area after the boss battle. You are given a stone that allows you to be more easily summoned by other players. Not only this but while you are in their world your health, defense and attack are all boosted. As you rank up in the covenant you acquire spells/miracles that allow you to buff and heal your companions.
There would be 5 covenants in the game (1 for each world) that you could join at some point in the level.
Boletaria's covenant. Members are given a stone and invade people who have sinned by killing an npc or the old king. The covenant is joined by talking to the old king. Upon joining players are given a unique sword (not the demonbrandt) and the stone. They rank up in the covenant by killing players through invasion. Through ranking up the player gets a special armor and eventually gets a special sword that steals the essence of demons when they are struck. You gain 1% of your enemies souls when they are struck with it, but if you die while invading you lose all gained souls. In this covenant you can invade regardless of our form (human/hollow/spirit) but the victim loses no humanity or their body, only souls.
Stonefang tunnels covenant. This is a pyromancy based covenant taken by talking to an npc added before the Dragon God fight. Through this covenant you are given a better pyrmancy catalyst and a Red Soapstone allowing you to request duels. You rank up by beating people at duels and only people within the covenant can request duels. As you rank up you obtain unique pyromancies. The first being dragon's breath and the second being dragon's skin. The breath allows you to breath fire at a low mp cost, the second raises your physical defence and stamina regeneration. Finally you obtain dragon's body turning you into a dragon. Your damage and defence are slightly boosted. Your stamina regeneration is also boosted. However you cannot wear armor when using the spell.
Tower or Latria covenant. This covenant is joined after defeating the old monk. A servant of his hails you as the new old monk. You get a special invasion stone that allows you to invade worlds that have are already being invaded. You and the invader can do damage to eachother, but you do not leave until you kill the host. As you rank up you aquire new spells until you reach the highest rank you aquire a catalyst that allows you to cast any kind of magic.
Valley of Defilement covenant. This covenant is joined by sparing maiden astrea during the boss fight. She gives you her soul in return for your service to her. The covenant is a miracle based covenant. When you join you get the silver catalyst and a stone that allows you to draw invaders to your world. As you rank up you acquire better miracles until you reach the final rank you are given a special armor set that resists damage from dark spirits.
The Shrine of Storms covenant. This covenant is joined by resurrecting a body in one of the graves in the final area after the boss battle. You are given a stone that allows you to be more easily summoned by other players. Not only this but while you are in their world your health, defense and attack are all boosted. As you rank up in the covenant you acquire spells/miracles that allow you to buff and heal your companions.