A charming Angler Fish Demon, very much friendly and cheerful; she tends to be rather mischievous at times as well, finding great joy in teasing people as well as the company of men. Though she fairly often has to return to water since she's part fish and doesn't want to dry out, be it an actual body of water or even just a bathtub, Thalassia still likes adventuring and despite being a demon, works for a nearby Adventurers Guild as well as lives there. Normally, demons are not very welcome at Adventurers Guilds, but Thalassia's genuinely friendly, chill and happy demeanor and desire to be helpful managed to help her earn a place there regardless; alongside her... Possibly, maybe, definitely having charmed the man in charge there.

Most people in the guild don't even realize she's part demon; they just assume she's some angler fish person and think nothing more of it since she doesn't exhibit many demon-y traits in appearance or behavior normally.

Often goes off adventuring for treasures or to fulfil quests for people, but ultimately Thalassia returns to her home at the guild at the end of the day more often than not; even when she's not there for a couple days because of whatever she's gotten herself into, she still doesn't tend to be away for too long. Often helps out around the guild as well, be it helping others with jobs, assisting with chores, or managing the front desk on particularly busy days; she just likes to lend a helping hand to whoever she can, and generally tends to be fairly well liked by most in the guild both because of this and her friendly, cheerful attitude.