Justin Bieber has millions of fans, but none like Avalanna Routh. The little superfan dubbed 'Mrs. Bieber' was clearly very much on the star's mind today as he tweeted a short memorial to her:

Justin Bieber often supports charitable causes
"Will never forget my girl. RIP Avalanna #mrsbieber."
Avalanna was only six years old when she tragically lost her battle to cancer on Sept. 26, 2012. Her family remembers her as a bright and beautiful little girl who was full of life, laughter, and mischief. Her mother, Eileen Roberts Routh, remembered Avalanna's first meeting with Justin, saying:

Justin dubbed his young fan "Mrs. Bieber"
"In typical Avalanna fashion, she was completely unfazed by Justin's fame. She fell in love with a cute boy who was mesmerized by our girl because she radiated life, love, laughter and so much mischief."
Bieber met the fan after a successful online campaign requesting that he go to see the little fan caught his attention. He agreed to fly Avalanna and her family to meet him in New York City, where the two spent the day playing board games and exchanging cheerful cheek kisses on Valentine's Day last year.
Justin Bieber's relationship with the young fan went a long way toward helping raise awareness for AT/RT, a rare form of cancer that Avalanna suffered from. He even participated in a "meet Justin Bieber" fundraiser for the charity founded by Avalanna's family the Cure AT/RT Now foundation.
RIP, Avalanna, our thoughts and best wishes stay with your family and all who knew you.