When a three-year-old girl insisted Keegan Carnahan was a mermaid because she had pink hair, the 15-year-old decided to run with it.
Little Alidy, who Keegan babysits, was so obsessed with the magical creatures that she wore her mermaid costume every day.
And it just so happened that Keegan had a mermaid tail of her own tucked away in her wardrobe.
So Keegan decided to surprise the little girl, and she shared the adorable snaps on Twitter.
Alidy's mum, Jenna, told BuzzFeed News that Keegan's thoughtfulness had cheered her daughter up at a difficult time, as the little girl's father passed away last November.
Keegan's heartwarming tweet has been seen by more than two million people.