ishar-mla (arknights)
The sea dragon-like Leviathan named Ishar'mla, titled the "Corrupting Heart," is one of the four "Firstborn" of the Seaborn representing the power of "Migration." For millenia, He was sleeping deep within the "Mantle Ruins", an abandoned First Civilization underwater complex that Aegirians believe it was the birthplace of their civilization. It wouldn't be until 200 years ago when Maritimus, the famous anthropologist who was heading Aegir´s Fourth Mantle Ruins Expedition, made contact with Ishar'mla while exploring the ruins, awakening which led to him to be plagued by strange visions about the ancient civilization's downfall, and Ishar'mla devoring anything at His pass. He would later become a Seaborn after eating one of Ishar'mla's cubs not long after.
Ishar'mla was thought to be slain by the Abyssal Hunters during the great assault against the Leviathans as they were hiding within the ancient ruins of the abyss. However, it turns out that Ishar'mla's blood has merged with Skadi after the devastating battle and remained dormant for years. Due to its divine nature and His aggressiveness, the Sea Terrors tremble before Ishar'mla and the higher Seaborn refer to Him as their close kin.