FALON'DIN, FRIEND OF THE DEAD - WIKI PAGE

Falon'Din was said to be the elven god of death and fortune who guided the dead to the Beyond. It was also speculated that he and Dirthamen were twins, however, it is revealed that Dirthamen and Falon'Din were "twin souls" with no family connection. Their bond was not romantic, beyond even the strongest friendship. The oldest elven stories never even name them directly, referring to Falon'Din as "Dirthamen’s shadow," and Dirthamen as "Falon'Din's reflection." Together the twins accompanied the elders who would enter uthenera and walk the shifting paths in search of the secrets of dreams.

While there are Dalish tales that tell of him being gentle, wandering the Beyond to help lost spirits, there are also accounts that Falon'Din's vanity and desire for worshipers were so great he started brutal wars to gain more, killing all who would not bow to him. Only once Mythal rallied the other gods and they attacked Falon'Din in his own temple did he surrender. Even Solas speaks of his vanity and appetite for adulation. It is therefore easy to believe that Falon'din willingly partook in Mythal's murder, taking Dirthamen with him.