Interesting to read, KC. I doubt we'll ever know how this came about. Nature can be quite surprising... although I've a feeling I know how it will end.
Years ago, in Africa, there was a young Antelope that was adopted by a Lioness. Nobody knew how this happened or why, as the Lioness should have eaten the Antelope - instead they hung out together like siblings. The Antelope had no fear of the Lioness, and the Lioness treated the Antelope like a younger brother/sister. You can guess how this ended, can't you? Another Lion came along and ate the young Antelope.
I'm not 100% sure it was an Antelope, as it was a long time ago, but the whole thing was filmed, so the video of the two friends is probably on Youtube somewhere... although be prepared for the sad ending.