The relationship between the supreme deity of a setting and the devil or The Anti-God can vary wildly. Usually they're arch-enemies, sometimes allies or friendly enemies. Maybe the latter works for the former. Sometimes, however, Satan's relationship with God is more personal than just a former servant, and the God of Evil isn't just the Foil to his God of Good. Sometimes, they're family.
Given God is supposed to have directly created the angels, especially Satan, it's easy to interpret them as His children. With this, the Devil is as much the ultimate rebellious son as he is a rebel angel. Maybe that's why he often hates humanity; he's jealous of the attention they get from his Father. Satan may not even truly hate God, just want his attention. This can work to make Satan's status as God's enemy all the more personal by being his son, or make the devil more sympathetic through a family. If God and Satan Are Both Jerks, God could be Satan's Freudian Excuse. Other angels, mainly Archangel Michael, would complicate things by being the other children and Satan's siblings.
Of course, not all supreme beings have some kid with Daddy Issues messing with their divine plan, but a God of Evil or The Anti-God that's as powerful as them. Sometimes, the reason they're equal in power is because they are related, most often siblings. The Divine Conflict is thus often one of Sibling Rivalry. Being siblings it often implies they have a creator, who may be the true supreme being with the Top God and The Anti-God not on top of the pecking order like everyone thought.
Can overlap with Related in the Adaptation if based on religious/mythological figures, given while God created Satan religious thought usually doesn't think their connection is familial. Jesus or his equivalent may or may not enter into the equation assuming he even shows up. Often a cosmic version of the Dysfunctional Family. Compare Cop/Criminal Family for a version relating to human law.
- Lucifer: Both Lucifer Morningstar and Michael Demiurgos are considered sons of the Presence, though not the other angels. Lucifer's rebellion and journey throughout the series stems through his desire to escape his father's plan and shadow, and considering The Presence is The Omniscient it's exceptionally hard for even him to pull off. The Presence actually wants him to achieve this and admires his son's desire for independence, and is proud of Lucifer once he succeeds at escaping His plan.
- New Gods: While previously unrelated, ever since The New 52 Darkseid and Highfather have been brothers. While not the Devil and God figures of the DC Universe, they are the Top God of their half of the Fourth World and the New Gods mythos. That said, Darkseid's father is more powerful than both and far worse than Darkseid.
- In Spawn, God and the Devil are brothers and the second most powerful beings in the universe, surpassed only by the true creator and their mother(well, more parent) the Man of Miracles/The Mother of Creation. Well, were, since Post-Resurrection God has been retconned as the Man of Miracles anyway and them being related has been dropped.
- Hercules: Zeus and Hades are brothers, just as they were in Greek mythology, and retain their roles as King of the Gods and Lord of the Underworld, respectively. However, their placement is inverted, with Zeus being the older brother and Hades being the younger one, but they have a strained relationship and Hades even seeks to overthrow Zeus.
- In the book trilogy, House of Furies, God is known as The Shepard while the devil/satan is called Henry Morningside. Their twin brothers and share responsibly for guiding souls to the afterlife.
- N. K. Jemisin's Inheritance Trilogy: The three creator Gods Nahadoth, Itempas, and Enefa are siblings born of the Primordial Chaos. They're all of decidedly grey morality, but after Itempas' coup against the others, the state religion of the Arameri Empire portrayed him as the ultimate good and Nahadoth as evil.
- Similarly, "demons" in this setting are the half-blood children of gods and mortals, villified and hunted to extinction after it was discovered that their blood is a deadly poison to full gods. (Being both divine and mortal, their blood can infect gods with mortality).
- Quadrenes in the World of the Five Gods feel that the Bastard is an evil demon, but acknowledge that he is a son of the Mother, the Goddess of Summer. (Quintarians consider him more of an Odd Job God to be propitiated rather than sought, as he is still lord of demons and Hell.)
- The War Gods: Most of the deities on both sides of the good-evil divide are the children or grandchildren of the creator deity Orr. The only exceptions are Kontifrio (Orr's wife — directly created by him, but not that way), Trickster God Hirahim Lightfoot (no one knows where he came from), and Shigu (a demoness raised to divine status by Satan-analogue Phrobus when he decided he needed to breed his own pantheon to challenge Dad).
- Like the original comic, Lucifer (2016) has God and the titular Fallen Angel have a strained father-son relationship. He also has a mother in the form of the Goddess.
- All the angels are considered siblings with God, eventually revealed to be Chuck Shurley, as their Disappeared Dad. Lucifer used to be God's favorite son before his fall. His hatred towards humans is down to jealousy over God paying attention to them over him. Or less charitably, a brat throwing a tantrum. That said, he's far from the only angel with family issues.
- Initially Death was considered The Anti-God to God/Chuck, however Season 11 reveals the true anti-god is God's older sister Amara, who's the Destroyer Deity to Chuck's creator deity. She serves as the Arc Villain but unlike most anti-gods ends up reconciling with her counterpart and brother. The aforementioned angels refer to her as their aunt.
- Mormonism: According to the Mormon faith, Satan and Jesus are brothers, both being the sons of the Old Testament God. Unlike most interpretations they were born naturally rather than being created/an aspect of God. They still end up feuding with one another, though.
- Zoroastrianism has Ahura Mazda serve as the God of Good and the Top God of the religion. Angra Mainyu, the God of Evil and equal, is considered to be Ahura's Evil Twin. The Zurvanism sect even posits they were twins in the womb to the androgynous Zurvan, their parent and the god of time.
- In a Jeff Allen special Teenagers are God's revenge he compared Satan to a 16 year old who is in his teenage rebellion years, and after getting his license he drove to Georgia.
- Dungeons & Dragons: Some sources portray Heironeous, the Lawful Good god of justice and honour, and his Arch-Enemy Hextor, the Lawful Evil god of tyranny, as estranged brothers. They're both War Gods but have diametrically opposed philosophies.
- Pathfinder: Ragathiel, the empyreal lord of chivalry, duty and honor, is the estranged son of Dispater, the Iron Lord of Dis and one of the nine archdevils. Ragathiel takes a very direct role in battling the forces of Hell, in large part to prove to both himself and the rest of Heaven that he has no link to his father's evil. Dispater, for his part, considers this to be essentially a fit of teenage rebelliousness and expects that Ragathiel will return to him in time.
- BIONICLE: In the early storylines, Big Bad Makuta was introduced as the "brother" of Mata Nui. Later plots revealed that not only was Makuta a completely different species from Mata Nuinote , Mata Nui is the giant robot that every other character lives inside.
- Transformers: In a similar vein to Zoroastrianism, the franchise has Cybertron's God Primus and God of Evil Unicron be warring brothers. Their "parent" is a mysterious being known as The One, hinted to be The Maker or the true God of the setting. Unless Unicron has an origin different from "ancient dark god".
- Casey and Andy: Satan (who is portrayed as an attractive young woman, and is also Andy's girlfriend) is shown talking to God, Whom she refers to as "Daddy" (and Who at least sometimes refers to Satan as "my little girl").
- Dead Duck: The devil in this series is revealed as the teenage son of God. Teens being rebellious and all, you can see how that would put them at odds.
- The Simpsons: "Treehouse of Horror VII's" segment "The Genesis Tub" has Lisa unknowingly create a miniature civilization, leading to them shrinking her down and worshipping her as their god. Because Bart squished the Petri dish, they think he's the Devil, and were quite perplexed that Lisa said he's her brother.
- Star Wars: The Clone Wars: The Mortis arc has the Father, the Son, and the Daughter, who each represent different aspects of the Force: The Son (or Brother) represents the dark side, the Daughter (or Sister) the Light, and the Father attempts to keep the peace between them.