By Debra Killalea
Most animal lovers would be happy to have a dog, or even a cat as their constant and loyal companion.
But naturalist Casey Anderson has taken that a step further and adopted an 58-stone grizzly bear called Brutus, who he has raised since birth.
The pair are inseparable and are so close that when Anderson married Charlie and the Chocolate Factory actress Missi Pyle in August last year, the bear stood in as best man.
Naturalist Casey Anderson is so close to 800-pound Brutus that when he wed actress Missy Pyle last year, the grizzly bear acted as best man
Brutus and Anderson set out on a year documentary called Grizzly Expedition which chronicles the lives of Yellowstone Park's bears
In fact, the creature is so fond of humans that he has become an integral part of the family, and even has the occasional place at the kitchen table and has appeared in a move with Pyle.
And while most cynics might argue the pictures are the result of Photoshop technology, Anderson and National Geographic have vouched for their authenticity.
The couple would never have dreamed of leaving Brutus out of their nuptials
'He's my best friend,' Anderson told Good Morning America. 'He gives me unconditional love.'
Anderson said the creatures were his passion and it was his aim to educate the public about how important it was to preserve their environment.
Anderson insists grizzlys are misunderstood and aims to educate the public about the real nature of the creatures
Anderson's relationship with Brutus began seven years ago when the cub was taken to an over-populated nature reserve and faced being destroyed
He added many people wrongly assumed that bears were blood-thirsty man eaters which in fact the opposite is true and they normally shun human contact.
'It's the biggest misconception. When you hear about a grizzly bear, it's because they have done something wrong.' Anderson said.
'We're trying to cure the myths, educate the public.'
He added there was a way of coexisting with these animals but that humans had to play by the rules.
Anderson said it was his mission to raise awareness of the struggles bears face on a daily basis
Anderson takes his then young cub out for a late-night stroll
He also insists the creatures are similar to humans in that they are intelligent, have personality, and according to him can even shed tears.
It is his passion for the creatures that sparked Anderson to set out on a year-long mission to chronicle the lives of Yellowstone National Park bears.
Together with National Geographic, Expedition Grizzly aims to dispel the negative stereotypes surrounding the bears and chart the impact humans have had on their environment.
In the documentary, which is due to air on National Geographic on May 3, Anderson lives among the bears, often in extreme conditions as he observes their behaviour.
He even eats some of the food they do as he observes their daily struggles throughout the seasons.
Mr Anderson, who created the Montana Grizzly Encounter animal sanctuary, said it was his friendship with Brutus that prompted him to take action on preserving the creature's futures.
The pair's unlikely friendship began seven years ago, when Anderson met Brutus in a wildlife park where the then cub was born.
The pair are so close they do everything together, including cooling off in the bath
Too cool for pool: Brutus is allowed to roam and swim wherever he likes
The reserve suffered from over-population, and Brutus was destined to remain in captivity or be destroyed.
He adopted the orphaned cub and began the sanctuary so Brutus 'could act like a real bear.'
And while most partners might be put off by a third wheel in the relationship, the new Mrs Anderson would not have it any other way.
Little Brutus has become an integral part of the family and loves human contact
Brutus is never left out and even joins in the Anderson family thanksgiving activities
The actress, who starred in Harold and Kumar Escape from Guantanamo Bay, has also formed an unlikely relationship with the bear.
The pair are actually acting buddies after Brutus appeared in her hit film, Pretty Ugly People.
By nature, grizzly bears are intelligent and inquisitive creatures and usually have no interest in harming humans.
The best friends take a much-needed break during filming
Anderson reveals bears, like humans, are intelligent and feel emotion and love
In rare cases when they do attack, they do so because they feel threatened, or a mother feels her cubs are under threat.
Grizzlies mostly consume vegetarian food such as berries and roots, but will eat what other animals have killed.
The animals have to eat 35 pounds of food daily and can weigh up to 1,200 pounds.
Brutus stars in the National Geographic documentary and stays by his best friend's side throughout filming
Brutus shows his strength and gentle nature as he gives his special friend another high five
Man and beast have formed a lifelong friendship