We love to keep pets, forming close bonds with them, and making them part of our lives. But around the world some people have sought out unusual - and even potentially dangerous - relationships, with some very surprising animals.For a human to want to befriend a lion or a buffalo is one thing, but why do these animals also form close relationships with us? Can science help us understand how a hippo can become part of the family? Why would a polar bear let a man give her a hug? And how it is possible to join a pack of hyenas without being attacked?Wildlife biologist Liz Bonnin is on a worldwide journey of discovery to uncover the reasons behind some of the most unexpected friendships between animals and humans. She wants to find out how these relationships are formed, why they work, and what's in it for both the humans and the animals.