19-year-old Ethan and 17-year-old Alana McMullan are more than just brother and sister, they're best friends.
From Mississippi, the pair loved going bowling together, until Alana was diagnosed with a brain tumour.
"She has had the tumour for a very long time but we just found out about it on 6 March and had her surgery on 14 March," Ethan told Buzzfeed. "She's coping really well and staying positive about everything."
In an act of big-brotherly love, Ethan got a stylish haircut after his sister's surgery- to represent her scar.
i have the best big brother. #braintumoraintgotnothingonme #twins pic.twitter.com/nZiX1QNvrS
— A L A N A (@alanamc_12) 17 March 2018
Alana was so emotional about her brothers touching gesture that she shared it on Twitter- where it has since gone viral.
"I got the haircut just to show her that she wasn't going through all of this alone," Ethan added.
He continued to say that he wanted "to show her that her scar was something to be proud of and show off."
I love my little sister! Time to kick this tumors butt!! #twins #McMullanStrong pic.twitter.com/ntuuwS7gb6
— Ethan Lee McMullan (@Ethan_mcmoney) 18 March 2018
This thoughtfulness paid off and Alana adored it.
"She loved it when she saw it!"
The viral success of the pictures have come as a shock to the family.
"I love that everyone has seen my hair cut but I'm just glad that everyone is seeing it and praying for her," Ethan concluded.
We're emotional just looking at the pictures!
— Laura Rushing (@lalalarushing) 17 March 2018
These little things will mean more than u could have ever imagined
— Sha Alderman (@jsalderman) 17 March 2018
— (@mchurch_) 19 March 2018
I dont have an older brother, but I would totally do this for my little sis
— (@AnulRamirez) 19 March 2018
We’re scar twins! Brain tumors are a horrible thing but they ultimately make you and those around you stronger. Keep your head up beautiful!
— Elizabeth Meri (@Lizzybeth1397) 20 March 2018
Pass the tissues please, I seem to have something in my eye.