Pop superstar Justin Bieber has paid tribute to six-year-old fan Avalanna Routh one year after her death. The Never Say Never hitmaker took to Twitter.com on Thursday (26Sep13) to remember the superfan he called Mrs. Bieber. In a message on the social networking site, he wrote, "Will never forget my girl. RIP Avalanna mrsbieber". Bieber met Routh in February 2012 and stayed in touch with her until she passed away from brain cancer in September 2012. He even staged a fake wedding ceremony to make her his 'wife'. Routh suffered from a rare and aggressive form of brain cancer called AT/RT. Bieber also remembered his tragic young pal on what would have been her seventh birthday last October (12), tweeting, "Today would of been the 7th Birthday of Mrs.Bieber. @Avalanna you changed my life. We will all celebrate you today no matter what. love u."