Your Constitution score increases by 1, and your Charisma score increases by 2. However, your Dexterity score decreases by 2. 

Mermaids reach maturity around age 15 and can live up to 200 years.

Mermaids tend toward good alignments, but are equally likely to be either lawful or chaotic. 

As a Conjoined Mermaid Twin, you reach a total of around 8 feet in length. You are still classified as a Medium creature. 

You have a swimming speed of 30 feet, but since you have no legs you can only crawl along the ground with a walking speed of 5 feet. Thanks to their limitation on land, they are consistently considered prone and are thus immune to the condition. 

You can breathe air and water.

You are beautiful by almost everyone's standards. Therefore, you can dazzle others with your visage and song. You gain proficiency in Persuasion.

You can see in dim light within 60 feet of you as if it were bright light and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

Aquatic beasts have an extraordinary affinity with your people. You can communicate simple ideas with beasts that can breathe water. They can understand the meaning of your words, though you have no special ability to understand them in return.

Adapted to the frigid ocean depths, you have resistance to cold damage.

You can speak, read, and write Common and Primordial.