Seven Deadly Sins

The Seven Deadly Sins also known as The Seven Evil Dragons of Satan are the seven powerful spirits that were created by the Original Satan as a weapon against Angels and Fallen Angels. They were Satan's first seven children and were his most powerful. The were however imprisoned, in a tomb in the human world due to their own destructive nature by the current Four Great Satans along with Seth Alastor and Camilla Pendragon. It is stated that during the Apocalypse they will pick a side, either working with the Christ or Antichrist, they will however choose the one who will try to rule over all the worlds, a "Prince of Chaos" as they claim.

Summary
The Seven Deadly Sins were created by the Original Satan who created them by harvesting the sin that was released throughout the human world by Adam and Eve after they ate from the Fruit of Forbidden Knowledge, he combined the massive amount of energy created by Sin along with his own dark light ability to create the seven deadly sins. Because they were created by a massive amount of energy, they became known as Evil Dragons. Satan thus trained them to become his seven knights and they were known to be the strongest soldiers in Satan's war against God, being feared among the Heaven and the Underworld.

In response to their creation, God created the Seven Heavenly Virtues from the good and virtue of humans which became known as The Seven Generals of Heaven, the two sides waging war for generations, each with their own army of demons and Prophets. After the death of the Biblical God and The Original Satan the two sides fought without restraints and the Seven Deadly Sins would try to conquer the Underworld and Earth because they had no father holding him back, in response the Four Great Satans used Seth Alastor's Power of Soul to seal them away on the Earth behind 66 Seals.

After the Sealing of the Seven Deadly Sins, the Seven Virtues, decided to be sealed in Heaven, due to seeing no reason for them to exist anymore. It is noted by Ddraig that the Seven Heavenly Virtues were never considered dragons by other dragons because they refused to act impulsively, freely, and selfishly, only following the will of their father. When Ichiro goes to Heavenly, he sees a statue of the seven generals.

Pride
Pride is noted to be the strongest of all his siblings, stating that he has power on par to a Ultimate-Class Devil while his siblings are noted to only be upper high-class devil level. Pride however states what makes him the worst sin and strongest of all is because it was his father's pride that led him to challenge and oppose God. Pride also states that a person who is filled with his sin will never admit that they are wrong, believing that they are perfect. When he is enraged, it is noted that dragon scales will appear on his neck, arms, and cheeks.

He possesses the unique ability to craft illusions, being able to generate black smoke and anyone it touches will fall under his power. Pride also possesses powerful lightning-based magic that has both demonic and dragon slaying properties it it, making it incredibly powerful against angels, fallen angels, and dragons.

Envy
Envy possesses power on par to a high-class devil. The sin she represents is noted to be considered worse than pride however not as strong. Envy is wishing to hurt others because they were either better than you in some way, this sin is a branch connected with Pride. She is noted to be second-in-command of her siblings despite not being the strongest but because of Wrath's short tempered she was assigned the position by her father, and she also possesses two dragon wings signifying her position as a dragon.

Envy possesses the ability of possession, she is capable of possessing others, even high-class or ultimate-class devils like Diehauser Belial or Serafall Leviathan can become victim to her power, however the stronger the being the harder it is to contain them. She can also release immense water and ice-based magic that similar to her brother Pride has immense dragon slaying and demonic properties imbued in it.

Wrath
Wrath is a terrible sin that leads to anger. This sin when put at the root of your heart leads to war, chaos, and murder. Wrath is connected to Envy as the envious suffers extreme anger towards the envied. Wrath is the physically strongest out of all the siblings. Because of her short fuse, it is stated that she can reach a state of outrage much more easily than the average dragon and in this state her siblings will consider her the strongest and almost unstoppable.

Wrath possesses the unique ability of power combustion, anything she touches she can set it to blow up. She is also capable of releasing blue flames that possess dragon slaying and demonic properties. Her flames are said to be on par to the Phenex Flames possesses by the Phenex family however much stronger in execution because they can completely fight against the fire of dragons.

Sloth
Sloth is a the sin that lazy people suffers, lazy people wouldn't care about anything and would not give effort at what s/he is doing.If forced to do a task s/he would find the easy and quick way to finish the task. Sloth possesses two dragon wings like Envy however unlike her, he doesn't use them to fly. Unlike his other siblings he doesn't prefer to fight as much and instead prefers to sleep however he followed them into war. It is also stated that when he was sealed he was a bit glad, due to now being able to sleep for a long time.

Sloth possesses the ability to make anyone who looks into his eyes fall into a dream-like state, he doesn't need any magic to use this ability as it is always on, however this can be warded off with protective and defensive magic and his siblings are immune to it's effect. Sloth also possesses the ability of teleportation, being able to move almost anywhere instantaneously. He can also move objects with his mind. Sloth possesses a unique form of magic known as similar to the Abbadon power of hole, he can summon magic sigils in his hands and mouth to absorb magical attacks and release it with demonic and dragon slaying properties.

Greed
Greed is selfishness taken to the extreme. This sin is connected to Gluttony and Envy. The Greedy will do just about anything to get more than enough be it money or other things. Greed was known for rampaging across the human world and Underworld to steal treasure, jewelry, and even money. He was hated among dragons and often pursued by others due to constantly stealing treasure, even crossing paths and stealing from Tiamat, having stolen some of her treasure from human thieves.

Greed possesses the ability to absorb minerals and objects from the earth and can summon it as dragon slaying demonic weapons, his power being equated to Sword Birth however he can't create weapons from nothing, instead needing to absorb or use the objects of others. He possesses a sword he named TitanSlayer, which was created using some of Tiamat's treasure that can summon gold, steel, or other minerals when swung.

Gluttony
Gluttony which is commonly believed to be the sin of over eating is actually the sin of wasting, although overeating can be part of it. Gluttony is over indulgence and over consumption of food, drink, or wealth items to the point of extravagance or waste. Gluttony was noted for his over consumption of the Dragon Apples on Earth before the climate changed destroyed them all. He was the last to be sealed, after all his siblings were sealed due to him hiding in a small town in Europe, appearing as a dragon who threatened to eat all the villager's children if they didn't keep feeding him which led to a famine. He was later caught by Seth, and after a battle he was defeated and sealed. He is the only sibling with both a dragon and a human form.

Gluttony possesses no magic of his own, instead being a siphon, who needs to absorb magic from others via touch in order to use any magic in a battle. He also has the power to summon serpents to fight on his behalf. Glutton's magic allows him to summon powerful wind with both demonic and dragon-slaying properties in it. He can absorb wind as a sort of vacuum and release it from himself by clapping his hands together which can cause wind storms. The other sins have stated that if it wasn't for their father forbidding him from eating angels, he would've probably became a Grim.

Lust
Most people think Lust is the sin of wanting sex, well not just that, Lust is wanting to be constantly pleasured be it having sex or by being entertained or amused. Lust is noted to be the weakest of all the Seven Deadly Sins due to possessing almost no fighting capabilities of her own, instead acting as back-up or support for her teammates and weakening her enemies.

Lust possesses the unique ability to alter her physical appearance to anyone she desires and to communicate with others telepathically She can also tempt others into doing what she wants via kiss. She possesses powerful magic to strengthen her allies physically or magically, and can even heal her allies via physical contact, her healing however only works on devils, demons, or dragons and her touch causes immense burning or pain to angels and fallen angels.

Trivia

 * I thought of changing their order of strength based off the Circles of Dante's Inferno however this idea was discarded.
 * While the lore was created by me, I got some of the element ideas from this chat page: https://gamefaqs.gamespot.com/boards/288-creative-writing/73561794?page=1