Ddraig

"You will know soon enough. Get stronger for that coming day. I will give you my power any time you want. However, keep it in your mind that it will come with a sacrifice of something great. I will give you something that is worth the sacrifice. You can show it to those who laughed at you. The existence of a “Dragon” that is."

- Ddraig to Issei Hyoudou in Volume 2, End Game

Ddraig is one of the Two Heavenly Dragons and the arch-rival of Albion. He is called the Red Dragon known as the Welsh Dragon, Dragon Goch, Red Dragon Emperor and Red Dragon Emperor of Domination, who resides within the Longinus, Boosted Gear, wielded by Issei Hyoudou. He is feared among the Angels, Fallen Angels, Devils and the various other factions in the world for his destructive powers, which are said to be able to kill both Gods and Satans.

Appearance
Ddraig is a dragon with the appearance of a large red Western Dragon, with a long neck and green eyes. He also has red and golden spikes throughout his body.

Personality
Ddraig's personality has changed a great deal as time has passed. At first, he had a great deal of pride in himself, though he admits that he had an intense rivalry with Albion, the other Heavenly Dragon. Since that time, he has become somewhat depressed because of the fact that he has become known as the Oppai Dragon and the Breast Dragon Emperor. Ddraig even requires counseling and medication because of it. Ddraig has shown that he cares a great deal about his current host, Issei, as much as Albion cares about Vali, despite the fact that their hosts are the ones responsible for their demeaning nicknames.

He has also shown that he really likes his current lifestyle, which doesn't involve fighting his rival every time they meet, but knows that there will eventually be a time when he and Issei must fight Albion and Vali.

It also noted that unlike Albion he has an extremely high level of intelligence, as he can tell all things about mythological things just like Azazel. Although he and Albion are powerful enough to challenge Gods and Satans, they both agreed of avoid fighting Evil Dragons, claiming that they are more brutal than other dragons.

History
In the past, Ddraig was a fearsome Dragon known to have powerful flames that can incinerate anything including Gods and will never go out till it burns the opponents to ashes. Ddraig eventually met Albion, who was immune to his flames. Happy to meet someone who can rival him, Ddraig seals his flames and started to compete with Albion to improve themselves, developing techniques such as Boost and Transfer, and both eventually became famous as the Two Heavenly Dragon. During their many battles to improve themselves, both the Heavenly Dragons rampaged in the Realm of the Dead. Ddraig also fought against Grendel and Níðhöggr at an undisclosed time in the past.

At some close point also in the past, Ddraig had borrowed Tiamat's treasure for his upcoming battle with Albion and was accidentally destroyed during the fight. Since then she has been chasing after Ddraig and his possessors for a long time, to retrieve her stolen treasure, however Ddraig himself is not aware of this (until Tiamat revealed it in Volume 23).

At one point, while continuing his battle with his arch-rival, the Vanishing Dragon, Albion, which was interrupted by the Angels, Devils, and Fallen Angels who were at war during the time. In anger, both Dragons attacked the leaders of the Three Factions, which led to their bodies being destroyed and their souls being sealed into two separate Sacred Gears, with Ddraig being placed inside the Sacred Gear "Boosted Gear".

Over the centuries, Ddraig has met with countless hosts possessing his Sacred Gear, some of whom have faced off against possessors hosting Albion's spirit to continue the Dragon's long lasting rivalry, up until his current host; Issei Hyoudou.

The Red Dragon Emperor's Awakening
Ddraig appears in the beginning of Volume 2, introducing himself to Issei. He reappears after Issei’s defeat at the hand of Riser Phenex, telling him about the "White One". Issei made a deal with Ddraig to temporally use Balance Breaker so he can face Riser again to save Rias in exchange for his left arm which was turned into that of a Dragon.

Birth of the Breast Dragon Emperor
In Volume 3, after being silent for a while, Ddraig had a conversation with Issei regarding "White One"; Albion, the White Dragon Emperor. The two eventually start a teacher-student relationship about many things regarding the mythological world, while Ddraig also gives advice to Issei during his fights, such as the later fight against Kokabiel. The said fight was then interrupted by Vali Lucifer, the current host of the White Dragon Emperor, who finished off Kokabiel instead. Ddraig briefly talks to Albion about the awaited match between their current hosts.

In Volume 4, after Issei meets Vali again, Ddraig explains the history between him and Albion. During the crisis with the Khaos Brigade attack, Ddraig cooperates with Issei in his fight with Vali and even supported him surviving in taking Vali's ability which created the Dividing Gear.

In Volume 5, when Issei attains the Balance Breaker after poking Rias' breasts, Ddraig was happy but sad at the same time. He then told Issei that he is seriously going to cry someday.

In Volume 6, Ddraig cried for the first time after hearing the television announcer of the Underworld calling Issei the "Breast Dragon Emperor" and "Oppai Dragon" after the Rating Game with Sona Sitri. After Shalba Beelzebub supposedly killed Asia Argento, Ddraig warned Rias to stay away from Issei as he was about to enter Juggernaut Drive. Later, while Issei was unconsciousness due to the effects of Juggernaut Drive, Ddraig explains to Azazel the usage of the form and its major drawbacks, such as the user going berserk and using up most (if not all) of their life energy.

The Heroic Oppai Dragon
In Volume 7 when attempting to talk to Albion, who shunned Ddraig claiming that he does not have any Breast Dragon Emperor rival, the two of them cried together. While crying, Ddraig protested, claiming that it is all Issei's fault as the two of them questioned how the two proud Heavenly Dragons had become like this.

In Volume 10, Ddraig privately contacted Azazel through Fafnir's jewel to ask him to search for a Dragon Counselor as he has been crying unconsciously.

In Volume 11, it is revealed that Ddraig suffered a broken heart at the hands of Issei, crying upon hearing the word "breast", and requires medication as well as counseling (10,000 years, to be exact). However, upon Issei's 'death' Ddraig still states Issei was the greatest host of Boosted Gear ever.

In Volume 12, Ddraig is able to capture Issei's soul and attach it to the Scale Mail, and with the aid of Ophis, transferred Issei's soul to a new body crafted by Great Red from his own flesh. After the battle with Cao Cao, Ddraig found himself exhausted, and fell into a deep sleep, after making Issei think he was dying.

The Legend of Oppai Dragon and his Lively Companions
During the first half of Volume 14, Ddraig was still sleeping after using up most of his energy to help restore Issei's body. He later awakens with the help of Fafnir and Vritra during the attack on Kuoh Academy led by Euclid Lucifuge and Grendel from Khaos Brigade.

In Volume 16, Ddraig tried to save Albion from breaking down mentally due to the appearance of Fafnir, telling him that Fafnir isn't the Dragon that they used to know and proceeded to enter a conversation with Albion, telling their possessors to be quiet for a while. Later, Ddraig was encouraged by Albion after the Two-Heavenly Dragons were mocked by Euclid Lucifuge.

Ddraig was absent for the most part in Volume 17 as he was trying to find clues on how Issei was able to use Albion's lost ability. With Albion, Vritra, and Fafnir's help, they were able to convince the past hosts of Divine Dividing to help them, resulting in Issei being able to use Dividing Wyvern Fairy freely.

In Volume 18, after searching deep within the Boosted Gear, Ddraig manages to unlock the ability Penetrate, which Issei uses to bypass Rizevim's Sacred Gear Canceler.

In Volume 20, when he and his friends went to Agreas, Ddraig re-meets Níðhöggr after a long time, before they fought him. Later Ddraig talks to Rizevim, telling him that he will be the first to witness Issei's new form that Ophis has granted him, Diabolos Dragon and gloats on how he is being overpowered by Issei.

Powers & Abilities
Immense Strength: As one of the Heavenly Dragons, Ddraig possesses great strength. Prior to being sealed within the Boosted Gear, Ddraig's power was stated to surpass that of the current Dragon Kings, Azazel also mentions that at their prime condition Ddraig and Albion are far stronger than the three known strongest Evil Dragons. Ddraig himself claims he has the power to destroy the world several times over simply through brute force.

Blazing Inferno of Scorching Flames: Ddraig's ultimate finishing move where he spouts out a powerful breath of flames which can incinerate anything that will never go out once ignited and can probably burn the soul, until nothing remains. Even Gods will be burnt to ashes within these flames. The only ones that it's ineffective against are Albion, Great Red and Ophis. Ddraig sealed this ability after meeting Albion.

Power Multiplication and Transference: One of the powers he develop during his rivalry with Albion. Ddraig is known for his ability to multiply his own powers or transfer that multiplied power into another being or object.

Penetrate: Another ability of Ddraig. It allows Ddraig to penetrate through all defenses.

Telepathy: Ddraig can communicates through people as he uses telepathy to communicate with Issei, Albion, Azazel, Rias and other Dragons.

Keen Intellect: Ddraig is a smart dragon, as he knows how to use all his powers properly that he usually teach it to Issei on how he completely utilize, use and control properly his full hidden and new powers properly. He is also wise enough to tell Issei the relationships and history of the Two Heavenly Dragons and regarding the mythological world.

Flight: Being a Dragon, Ddraig can fly using his wings.

Soul Transferal: Ddraig has the power to transfer the souls of other beings into other vessels. This was shown when he transferred Issei's soul into his armour and then into the vessel made from Great Red's flesh as Issei's original body was destroyed.

Quotes

 * (To Shalba) "—You... Made the wrong choice." (Volume 6, Juggernaut Drive)
 * "I want you to remember him. The man called Issei Hyoudou." (Volume 11, Life...)
 * "Yup, my name is Ddraig. I'm a baby Dragon." (Volume 14, Life 4)
 * (To Rizevim Lucifer) "Son of Lucifer. You think you’re his enemy? Even God of the Bible revered their power — dragons. Whether it’s me, or the Hakuryuukou, or Fafnir, you can’t underestimate us — I could if I wanted, to have destroyed the world a few times over with just brute force. But I haven’t done so, because compared to you, my life is more enjoyable like this." (Volume 18, Life 4)
 * (To Euclid Lucifuge) "Euclid Lucifuge. One Sekiryuutei is enough in this world. It's necessary for you to be defeated by us." (Volume 17, Life 4)
 * (To Rizevim Lucifer) "Shouldn’t you have known when you got involved? My partner — Hyoudou Issei has always been in pursuit of peace and quiet. But, whether it’s that descendent of the old Beelzebub, the leader of the Hero Faction, or even you, the son of Lucifer, you’ve all trampled over that which should not without a shred of hesitation." (Volume 20, Life 3)
 * (To Rizevim Lucifer) "Well, there is no choice but destruction, right? —This is the Sekiryuutei of the Two Heavenly Dragons. …No, this is something a bit different. This is something slightly different from the Two Heavenly Dragons, it should be known as the Cardinal Crimson Promotion — [ Diabolos Dragon]." (Volume 20, Life 3)

Trivia

 * Ddraig's name comes from the Welsh phrase Y Ddraig Goch, meaning "The Red Dragon". Y Ddraig Goch also appears on the flag of Wales as the country's national symbol.
 * In Welsh orthography, the letter "dd" is pronounced /ð/ as in  th at, so Ddraig's name should really be read as "Thraig".
 * If Ddraig or Albion were not sealed inside their respective Sacred Gears, their strength would place them among the Top 10 "Strongest Beings in the World".
 * Ddraig has called Issei by his name only once so far in the series.
 * Ddraig's title Red Dragon Emperor (赤龍帝) is loosely based from the name of the Pokemon Entei.
 * Ddraig was featured on WatchMojo's "Top 10 Epic Dragons in Anime" list, ranked at number 10.