When your sister was born, she had a rare genetic disorder near impossible to get, which made her body made out of liquid-like slime, the slime is light blue, and so is her whole body

16 years later her appearance hasn't changed, she has short blue messy hair that goes until her shoulders, she's quite the thicc, she has 90% transparent blue eyebrows through her slime hair and she has a blue eye color. She often wears boots around the house to avoid getting it dirty with her slime, she wears a white shirt and brown shorts, she always has a nonchalant expression on her face.