When Isabel Klee adopted Simon in 2019, she knew he was a special pup. But there was no way for her to know just how special the rescue dog was, or that he would be mourned by millions when their life together came to an untimely end.

Countless people are celebrating the life of Simon, also known as the world’s best foster brother, as he crosses the Rainbow Bridge. For several years, Klee has shared the journeys of the dogs she fosters on TikTok and Instagram under the handle @simon.sits. Fans have watched in awe as Simon patiently and intuitively responds to every dog Klee has brought home. Klee has a magical way of healing dogs from every kind of background and situation. And Simon has been right there with her, tail wagging like a magic wand, giving each strange dog whatever it needed to feel safe and loved.

@simonsits The greatest love story I’ve ever known 🥹 ♬ Grateful – Dusty Grey

The greatest love story I’ve ever known 🥹 ♬ Grateful – Dusty Grey

Battling a seizure disorder complicated by cancer

Over 13 million people watched Tiki, a terrified, traumatized dog, come to life under Klee and Simon’s care. Fans around the world have made household names of Klee’s foster dogs—Tiki, Whimsy, Raven, Marmie, and so many more. But the constant, steady presence of Simon ran like a thread through each of their stories.

Klee calls Simon the love of her life. For those who have watched them together, the heartbreak of losing him is palpable. As a medically complex dog, Simon’s health was a serious question mark from the get-go. He had a seizure disorder since he was a puppy, which they always had to manage. But a cancer diagnosis this past year complicated his health........

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