"To hear the god emperor describe it, Crimson’s breath channeled the Gate of Creation into a lance of fire so hot it could cut the planet in two. When the Dragon Wars erupted, Crimson attacked the All Father and was cursed to lose his eldar magic."
- Dar Tania, Dar Tania II: Set's Dream
Of all the eldar dragons, only a handful approached the heat burning in the Gate of Creation and Chaos before they split apart. Crimson Burning was the hottest. His real name, Bvocpharan Mae’yl, was lost until Alerius chose to reveal it to the Sage Alaura and Dar Tania upon sanctification of the Temple at Morbatten.
As noted in the histories written by the Sage Alaura, the Dragon Wars began as a philosophical disagreement, but there was some fighting. When the All Father made clear his intent to join Heaven and turned to leave, Mae'yl said "no" and attacked. The only dragon to attack the All Father and survive, the attack helped push Tehra into Time's flow. The All Father cursed Mae'yl for his attack and cast him back into Tehra. The curse stripped Mae'yl of many eldar powers, locked his shape, quieted his voice, and removed his eldar magic. His titanic form remained as did his god-like breath weapon. Not to be outdone, the All Father bound Crimson in the molten core of Tehra.
When Dar Tania consecrated the Temple At Morbatten in 12 DAR, Crimson was released, but stayed aloof from Tania and Alerius' objectives. Ana though had a fascination with Crimson and spent all of her spare time with him in Alerius' mountain. Following the 1st Cascade in 350 DAR, Crimson came out of seclusion and joined Ana in her first assault on Bloodstone in 430 DAR. Ana now serves as his rider. He is the guardian of the Temple At Bloodstone. Though he cannot speak, Ana has learned how to read his body language and can effectively communicate on his behalf via their rider bond. She explained once, in a letter to the god emperor, that Crimson went into seclusion because he did not think there were any enemies left to fight amongst the fallen mortal races. The 1st Cascade showed him enemies worth fighting.
Like Alerius, Arminoth, and Armageddon, Mae'yl can shape his breath weapon however he pleases. While sages can speculate, even Alerius acknowledges that Mae'yl could defeat him easily in a fair fight. Alerius' mastery of magic gives him the edge. Thankfully, Alerius and Mae'yl regard each other as peers and equals. To further cement the relationship, Mae'yl was created directly by Takhissis which makes him a proxy son to Alerius though there is no direct family linkage with Mae'yl being a created being, same as the other eldar red (Armageddon and Arminoth) - all of whom were created by Takhissis rather than birthed through a mating.