Dark Sun Gwyndolin

Dark Sun Gwyndolin was the youngest son of Lord Gwyn, the de-facto ruler of Anor Londo and an integral character in the lore of Dark Souls.

Appearance
Being a god of Anor Londo, Gwyndolin has a very unique appearance. He wears white silk robes and a golden crown meant to represent the image of the sun.

He also has a very feminine physique, appearing to posses breasts even though he identifies as male. He also has pale skin and silver/grey hair. This is possibly due to his link with the moon. In the place of his legs, there appears to be snakes. Whether or not these snakes are illusions or real, is unknown.

In Dark Souls III, Gwyndolins appearance has changed. He wears a new set of dark clothing with gold woven into it. His crown is also different and not quite as ornate as the one he wore before. His health has also deteriorated drastically, becoming severely malnourished. This is most likely the result of Aldrich slowly digesting his body. His lower half is no longer visible, Aldrich having already devoured it.

Personality
Gwyndolin seems to hold a "deep adoration for the sun", including his father and livelihood. He has a deep desire for his father's affections, and not only does he cast in illusionary sunset over Anor Londo to create the illusion of a prosperous city, but he even guard's his father's tomb himself, attacking the Chosen Undead should they trespass, even though he is fully aware that the tomb is empty.

Given his power of illusions, Gwyndolin is appropriately a masterful schemer. His illusion of Gwynevere is used to trick the Chosen Undead into linking the fire and continuing his reign in Anor Londo.

Powers and Abilities
As a god like the rest of his family, Gwyndolin was immortal, living beyond the human lifespan. Curiously, he has access to a variety of illusionary sorceries so powerful they range from hiding pathways behind walls to boosting the guard's threatening demeanor to even casting an illusion over the entire city, disguising it under a false sun.

Gwyndolin is also a skilled archer, using his darkmoon bow to fire arrows of pure light.

While technically immortal, his eternal life was not absolute. Like other gods, he could be killed by another, be it by the Chosen Undead's hands or by Aldrich, and even fell ill by the events of Dark Souls III. As a god, he is also vulnerable to occult weapons.

History
Eons after the war between the gods and the dragons, Gwyn established his own kingdom in Anor Londo where he married and had children. Gwyndolin was the youngest of his sons, and because he possessed inherent abilities associated with the moon (which was considered a feminine trait), was raised as a daughter.

When Gwyn left to the kiln of the first flame to link the fire and stave off the Age of Dark, he told his family to look after the humans in his absense. Not wanting to let him down, Gwyndolin sought to keep the humans safe and soon had humanity coralled to the north or exiling them to stone prisons to keep the curse of the undead under control.

All other deities in Anor Londo would soon leave as well, horrified by what was happening. Gwyndolin however decided to stay in the now abandoned city of the gods. Using his power over illusions, he creates an illusion of his sister Gwenevere to help guard over the city.

Despite his lackluster status as a deity, he does manage to gather a group of followers called the Blades of the Darkmoon, a covenant created to find and hunt down those who are guilty of crimes against the gods and claiming vengeance. They accomplish this by reading out a list from the Book of the Guilty from Goddess of Sin Velka.

Dark Souls
When the Chosen Undead reaches Anor Londo, battling through guards, demons and royal knights Ornstein and Smough, the Chosen Undead reaches the illusion of Gwynevere, who will tell the player that they are tasked at linking the first flame and staving off the Age of Dark. Should the player attack the illusion, Gwynevere will disappear, undoing the illusions cast over Anor Londo.

For this blasphemy against his family, Gwyndolin angrily reveals his presence and will proceed to send his covenant to kill the Chosen Undead. He then fights the Chosen Undead himself when trespassing into Gwen's tomb, where Gwyndolin supposedly dies.

Dark Souls III
It is revealed that Gwyndolin survived the events of Dark Souls and is living out his days in what was left of Anor Londo. After some time however, he contracted an illness so severe that he was no longer capable of leading his covenant, the Darkmoon Knights, which meant his younger sister Company Captain Yorshka had to take command in his stead.

After Aldrich was revived as a Lord of Cinder, he began dreaming of the Old Gods and sought to devour them. Sulyvahn traveled with him to Anor Londo and managed to capture Gwyndolin, who willingly sacrificed himself to save Yorshka. She managed to evade capture but Aldrich devoured and assimilated Gwyndolin, who became the upper body of the abomination, as well as Gwyndolin's abilities.

After devouring Gwyndolin, he fell into a deep slumber and dreamed about a young, pale girl in hiding.

Trivia

 * It is implied through the illusion of his sister that Gwyndolin is in-league with Kingseeker Frampt, one of the primordial serpents.
 * Dark Sun Gwyndolin is actually the head of two covenants at once. The first is the Princess Guard, a covenant ran by his illusion of his sister, and the Blades of the Darkmoon in his name.
 * It is implied that Gwyndolin was shunned by the family, or at the very least was treated as an outcast. Unlike his parents and older siblings, there are no signs of statues dedicated to Gwyndolin, the only traces of loyalty among mortals being from the Blade of Darkmoon covenant, a group founded by Gwendolin himself.
 * It is never explained why his lower half it composed of serpents supporting him, but many have theorized that he was experimented on by Seath the Scaleless, as not only does Seath and his Pisacas have similar features, but his boss music is the same as the Moonlight Butterfly, a monster created by Seath. This could also explain Gwyndolin's skill in sorceries, as while gods and their followers use the art of miracles, Seath the Scaleless was the founder and grandfather of all sorcery.
 * Another theory is that the serpents are in fact an illusion created by Gwyndolin meant to intimidate, hoping to compensate for his frail form.
 * It is very likely that the Gwyndolin the player faces and defeats in Dark Souls was an illusion, as it is revealed that he survived long enough to fall victim to Aldrich by the events of Dark Souls III.
 * It is also possible that Gwyndolin's death was written off as non-canon, seeing as how he was a completely optional boss and the player could run through the entire game without ever encountering him, as his soul wasn't required for the Lordvessel.
 * Given his title "Dark Sun", Gwyndolin shares much in common with many other outcast gods of mythology.
 * Despite being the eldest, Hades of Greek Mythology was the only member of his family not considered an Olympian, nor was he considered an idol of worship.
 * Gwyndolin's design holds a minor resemblence to Griffith from Berserk. This might not be a coincidence, as it is well known that Hidetaka Miyazaki, the director and producer of Dark Souls, openly took inspiration from Berserk in the design of Dark Souls.