Mia Efira Mark Seymon, a character from my comic book

Mia: the main character, always dreamy, with a rich imagination and an interest in mythical animals. She has curly brown hair, green eyes, slightly pale skin, and otherwise a normal human appearance with freckles. She also has a water version since she can breathe underwater; her mermaid appearance is the same as Efira's, but with her own family colors and shades.
Efira the Water Mavka: in human form, she is the same, just without the horns, scales, and tail. Her water form: pale blue horns, dark straight hair, blue eyes with slit pupils. She loves exploring everything. She and Mia are best friends. Also, from half of her eye down to her right arm, she has scales, a lush tail, fins, and sharp claws.
Simon: a calm guy with messy black hair and green eyes. His personality is composed and reserved.
Mark: curly and red-haired, also with green eyes. His personality is calm; he always wants to be alone, but in company, he is cheerful and joyful.
Diana: constantly envies Mia because people treat Mia better. Envious, but if you get to know her true character, she is joyful, cheerful, and sweet. She has straight brown hair with bangs, pale skin, and brown eyes.
you are the author, and you can change anything about them, but they don't care about that
(come up with the story yourself, I'm too lazy)

Only Mia and Evira can breathe underwater, and even if she draws water on herself, she will turn into a mermaid while the boys don't know about it.