From Elfish to Elf-Fish

Most of Barra'leth Kuuda's backstory is unknown. It's clear that he was once an Elf, but unfortunate timing of a job placed him right at the epicenter of a Turmoil event that turned the sleepy town of Muckwater upside-down.
 
The job in question was a routine one: deliver the documentation and silver amulets that would grant an incoming ship's passengers access to Ashport, a city under heavy quarantine at the time. While resting at the mayor's house, Barry somehow became transformed into a red-scaled fish-like person, reminiscent of the Mudfish regularly fished up there.
 
The transformation event appears to have altered his memory: he cannot seem to remember any events from before the transformation, except on some occasions where he is directly presented with a physical object associated with the event. For example, when given a longbow, Barry seemed to remember how to use it; when he encounters someone, he can recall if he's met them before.
 
During his escape from Muckwater, Barry acquired a hat of disguise that lets him travel throughout the world while appearing to be someone else, someone more "normal". However, he doesn't have a great imagination, so it seems like he can only masquerade as "normal" people that he's actually seen or met before...
 

It's All A Blur

When revisiting a chance encounter in Dazki Sylroris's past, the party witnessed an assassin named "Aathu Blurdrake" who shared a lot of mannerisms with Barry. Though Blurdrake was there to assassinate Dazki and his fiancée, that was only because of the interference of Pendel Codagio, whose underlings had altered something to rile up Blurdrake's blackmailer. It was never made clear what would have happened without Pendel's interference.
 
Regardless, present-day Barra'leth seems satisfied that the name "Aathu Blurdrake" might be one of his aliases, as it has all the same letters as his current name. Once he was shown an image of what Aathu looked like, he started making that disguise his default appearance.