User blog comment:Lord Loss/Monster Appreciation Week: Dire Miralis/@comment-6050823-20131012004307/@comment-11112316-20131013165751

Hm, I want to say Dire Miralis and Fatalis either share a similar ancestor, or one of the species originated from the other. Miralis is very specialized for its environment, and it seems the Tainted Seas or similar water areas are the only places Miralis could sufficiently thrive in. With its tendancy of killing most life in said areas, it can be assumed Miralis is a nomad of sorts.

My hypothesis is that Miralis is a heavily specialized off-shoot of the general Fatalis family. Perhaps some ancient Fatalises isolated themselves to semi-aquatic life styles, and Miralis eventually came to be. While it could be that the Fatalis trio descended from Miralis, I find the previous hypothesis to be more likely. Fatalises have very general bodies that occasionally aren't as efficiently adaptable to their environment--see Crimson Fatalis and its low health and quick anger due to the volcano's heat hurting it.

As for the immortality issue, I like to think both the Fatalis trio and Miralis are capable of sustaining their lives perpetually unless outright slain. We sadly have no knowledge on Miralis's life cycle and growth, but we can conjecture that Fatalis have extremely slow growth. Black Fatalis destroyed Schrade many eons ago, and it it is often considered the youngest in the family; Crimson Fatalis's age can't really be guessed, but it appears to still be growing due to the asymmetrical horn; White Fatalis has existed possibly longer than the ancient tower that may have been built to worship it, and (depending on how literally you take the title "ancestrial dragon") may be the ancestor of all or most of the true Elder Dragons. Personally, I doubt Miralis's heart is the cause of its immortality. It certainly helps keep it alive, but merely having a heart that never stops beating wouldn't deter other forms of aging and death caused by external means. It's an interesting gimmick, but not essential for living incredibly long, as seen in Yama and Fatalis.

This is just my thoughts, though. If anyone has any evidence or counters to my hypothesises, go ahead and shoot them.