How 2 very little girls forged a special bond while battling cancer together.

Sometimes the world just seems impossibly, horrifically unfair.

As they go through the darkest time in their short, little lives, 4-year-old Ava Garcia and 3-year-old Penny Smith have at least had each other. But now they are being forced to say good bye.

Ava was diagnosed with cancer of the kidneys last August, while Penny was diagnosed with skeletal muscle cancer in May 2014.

The pair became fast friends as they recovered together at Texas Children’s Hospital after surgery, before going through chemotherapy treatments side by side, every other week.

“It was like a play-date. Even though she was getting chemo, she was getting poked, it was stressful. It was easy going (to the hospital) knowing she was having fun,” Penny’s mother Cindy Sagan told WRIC.

And when Ava lost her hair, her mother Christina Garcia says, “It just made her more comfortable. She wasn’t scared because she looked like her.” Garcia says that having one another made the treatments less frightening for the girls.

The two mothers have also become close friends through the process and were hoping to celebrate their daughters’ remission together.

In February this year, Ava got the good news that she is now cancer free.

But a few weeks later Penny’s family was told she was dying.

Tragically, Penny’s health had deteriorated, with doctors giving her just weeks to live.

Ava visits Penny in the hospice where she now stays, bringing her cards and gifts.

“I don’t know how you tell a four-year-old that her friend’s not going to be here, not just a friend, a best friend,” Garcia says. “Penny got to enjoy enjoy having a best friend. Ava got to enjoy that and Penny will forever be in our hearts and we will always remember her.”

On Penny’s Facebook page, her mother has been documenting her daughter’s final weeks.

“At times she struggles with each breath. We’re still making changes to her pain meds to make them the most effective,” she writes. “She misses her friends and playing. She says, ‘Later, when I’m not sick’ and it freaking crushes my soul.”

Sagan told WRIC, “They are best friends through tragedy but they found each other and they’re going to hold on to each other for as long as possible.”

Sometimes the world just seems impossibly, horrifically unfair. These two little girls both deserve a shot at long, healthy and happy lives spent in each other’s company. The fact that only one will ever reach school age is the deepest of tragedies.

If you want to read more about Ava and Penny you can visit their Facebook pages here:

Ava Grace Garcia Facebook.

Penny Lane’s Battle with cancer.

If you would like to make a donation that will help support children battling cancer, you can do that here:

Ava’s Go Fund Me page.

Penny’s Give Forward page.