Solaire of Astora is a wandering, somewhat mysterious Warrior of Sunlight first met by the player after defeating a Taurus Demon. When he is spoken to and his request accepted, he awards the player the White Sign Soapstone, which allows the player to put down a soul sign and be summoned by others for jolly cooperation. He is beloved by the Dark Souls community for his amicable demeanor and continued assistance in fighting many challenging boss encounters.
Warrior of Sunlight Covenant
Solaire offers the player to join the Warrior of Sunlight covenant if certain conditions are met. To join, the player must have a Faith stat of 50. If the player doesn't have a Faith stat of 50, they can lower the requirement by being summoned and defeating a boss with another player. Each time the player is summoned and successfully defeats a boss, the requirement is lowered by 5. For example, a Faith stat of 10 would require the player be summoned 8 times (5x8=40) before the covenant is available.
Once the player has met the requirements, Solaire can be found next to the sunlight altar, located near the bonfire found underneath the bridge dragon.
As a Phantom
Solaire can be found at several different locations over the course of the game. If the player finds and interacts with him at each location, it allows him to be summoned for the area boss fight if the player is human.
If the player talks to Solaire outside the dragon bridge his bright gold soul sign can be found outside the fog door leading to the Bell Gargoyles boss fight. Solaire can be very helpful during this fight since he uses a lightning spear miracle that can do a fair amount of damage.
The player can summon Solaire for the Gaping Dragon boss fight provided they have already spoken to him. He's also fairly useful since he can draw the aggro of the dragon and act as a tank, although his limited HP means that if the player doesn't act quickly he won't last the entire fight.
Solaire can be found sitting next to a bonfire within Gwynevere's castle. Once spoken to, he will make himself available for summoning outside the fog gate leading to the Ornstein and Smough boss fight.
It's important to speak to Solaire here, since failing to do so will close off his progress through the rest of the game.
- Fourth Encounter: Sunlight Altar in Undead Burg / Demon Ruins - Centipede Demon
To make Solaire available for the Centipede Demon boss fight in the Demon Ruins, the player must return to the sunlight altar in Undead Burg after speaking to him in Anor Londo. Solaire can be found next to the sunlight altar and will offer the player a chance to join the Warrior of Sunlight covenant (provided they've met the requirements.) His soul sign can then be found outside the Centipede Demon fog door.
Solaire can be found just past the area where the player fought the Centipede Demon. Just talk to him to progress his path
This is where things get kind of complicated. In order to make Solaire available for the final boss fight, the player must ensure his safe passage through Lost Izalith by killing the red eyed Chaos Bug. If the player enters Lost Izalith normally, Solaire will become Hollow and attack the player outside the door leading to the Bed of Chaos boss fight.
In order to ensure Solaire's survival and assistance in the final fight, the player must take the shortcut to Lost Izalith found in the Demon Ruins. The shortcut is only accessible if the player reaches rank 2 in the Chaos Servant Covenant, which requires a sacrifice of 30 humanity. If the player is able to access the shortcut and kills the Chaos Bug with red eyes on the way to Lost Izalith, Solaire will be found outside the shortcut door. Speak to him to activate his summon sign for the final boss fight.
If the player ends up killing Solaire, they'll be awarded 1000 souls, 2 humanity, the Iron & Sun armor set (Iron Helm, Armor of the Sun, Iron Bracelet, Iron Leggings), the Sunlight Straight Sword, the Sunlight Shield, and the Sunlight Talisman. This is the only currently known way to acquire these items.