In 1969, John Rendell & Ace Berg adopted this lion, who they named Christian. After raising this lion for, like, 3 years they decided they needed to reintroduce him to the wild of Africa. 

A year later they wanted to visit, but were told Christian had become the head of his own pride, was now completely wild and would not remember them......well......

Sorry the video isn't great, couldn't find anything better.

Here's a bit longer version. I'm just so blown away by this. In a good way. It's remarkable. Shows what true love is. And that animals are NOT stupid.