NEW YORK (WHDH) -- Justin Bieber electrified Rockefeller Plaza Friday morning with a very special guest by his side: Avalanna, also known as “Mrs. Bieber.”

Little Avalanna Routh wouldn't dream of missing her man perform on the Today Show.

The 6-year-old from Merrimac has a very rare form of cancer.

Her love of all things Bieber gets her through her long days of radiation treatment. So much so, the Jimmy Fund even arranged a pretend wedding for her.

“There was a paper cutout of me and she did the whole wedding with the paper cutout,” Bieber told the Today Show’s Matt Lauer.

Thanks to a Facebook page set up by family and friends, the two have kept in touch ever since.

“We talk on iChat all the time,” Bieber said.