After she passed on Christmas Day, Rihanna shared a photo that they took together, along with a touching tribute to her departed fan.

"This Christmas, we lost a beautiful spirit who was such a pillar of strength to us! Most of our friendship she's spent in a hospital or doctor's office!" she wrote on Instagram. "This picture was just a few months ago, she looked at me and said 'Rih the cancer is back' I'll never forget the fear in her eyes this day!"

Rihanna made note of Monia's strength in battling three separate cancer diagnoses.  

"Still she pushed forward, fighting the fight everyday with the Navy behind her supporting her every step of the way!" she wrote. "We are all heartbroken about this!!! You will never be forgotten! Love you my angel @moniasto fly in peace."

Rihanna followed that up with another tribute. She posted a video of herself and Monia hugging with the caption "Miss you already, sis."

Rihanna lent her support to Monia til the end, even commenting on her last Instagram post to let her know that she and her fanbase were pulling for the sick fan.

"Sis we are all praying for you! Your strength and your ability to let the beauty in your spirit shine through, even in the midst of adversity, is tremendously inspiring!!" she wrote. "Thank you for continuing to share your journey with us! I imagine it's quite a lonely one, hours on end in hospital walls, being scared to even fall asleep because you're afraid u won't wake up, feeling like nobody will ever understand that, the physical agony, the medication and all their side effects...I can't begin to imagine what you feel, so I want you to know we are all here for you."