The stories of mermaids seducing sailors with their angelic songs are not completely unfounded. Once per short rest, you force a target of your choice to make a Charisma saving throw. If it fails, the creature becomes incapable of charming you and if any other creature tries to attack you during this period, the bewitched target will use whatever resources it has to defend you. The enchantment's effect ends at the end of the affected creature's next turn. The siren song effect does not prevent the target from attacking other players, only you. You also have an advantage on Persuasion and Deception tests.

You know control flames cantrip. 

Your Charisma score increases by 2, and your Wisdom score increases by 1.

Astral mermaids mature very slowly, and because of their rarity, the longevity of an astral mermaid is unknown

Astral mermaids' size is Medium.

Your base walking speed and astral swimming is 30 feet. Astral swimming mimics flying, but is only allowable in the astral sea.

You can speak, read, and write Common along with being able to speak to astral sea animals. Adapting to the astral sea gave you the found family who nurtured your development in their way of life as you also observed ships traveling through the astral sea.