Why do we love them?

On our walk this morning, I was ruminating on the idea of what it is to love another being - specifically a "non-human animal".  
What creates this bond?  Why can the loss of a pet be so very devastating?
Not uncommonly, we will have clients express to us that the loss of a pet hit them harder than the loss of a human family member.  How did this love come to be so deep?
Some clients have told us that they will never get another pet again after their beloved animal companion has passed away - that they cannot stand to go through a loss that profound again.
I mean WOW, that is a lot of emotion - a huge bond - with something that some people will describe as being "just a" cat, "just a dog", or even "just a" lizard.  

For me, my attachment to my dogs comes from the activities that we take part in, the adventures we have, or the training we do to learn a new skill.  We go through these things together: we share, we compromise.  We look into each other's eyes and smile.  We like the team that we are, and what we do.  For me, my dogs are not "fur babies", they are dogs, but they are unique and lovely individuals.  (Sometimes I tease our son that he's my "skin baby", just because it sounds creepy, and we have a weird sense of humor!)

Now cats.  I have cats.  I chose to have cats, but I love them differently.  Maybe not equally to the dogs.  (Is it OK to say that? Well, I'm blogging, so I say that it's OK.)
And I have great cats.  I think they like me too, sometimes!  Well, especially the one that is named Marco, AKA, The Yellow Peril.  
Marco isn't an easy cat.  He was a young adult rescue that transitioned to being an indoor cat quite well, until I kept a kitten from a litter of bottle babies that I had courtesy of the SPCA.
At this point, Marco decided that he would like to go outdoors, si vous plait, to escape our new kitten, Dwight.  Knowing the hazards of the Outdoor Life for cats, we heartily declined his request.  He continued to YELL at us that he would like to go outdoors.  We declined.  
We medicated Marco with neutraceuticals (Zylkene - ask for it at your local vet office, it really does work well for some pets), enriched his environment, changed his food, gave him safe spaces away from the kitten... Multiple litter boxes were provided.
Then began the revenge of the urine.  
Down the heating vents, Marco decided to urinate.  When he wasn't STILL YELLING AT US THAT HE'D REALLY LIKE TO GO OUTSIDE, he was peeing.
After replacing rusted, urine coated heating vents, we made the decision to give in.  And feel horribly guilty every damned time that we let him outside.  But now, no more bad peeing, and much less yelling from the cat.  He still yells a bit, because he cares.  Or because he can.  He's not saying which.
Oh, and Marco does not cuddle, he does not want to sit on anyone's lap.  He is his own cat, thank you very much.
But I love him.  And I think he has some small measure of affection for me.  He'll be sleeping on my bed, curled in an adorable cat ball, open his eyes, see me, and start to purr.  He reaches out a paw to encourage me to continue patting him, if I stop too soon.  He is pretty charming, if he does say so himself.  And yes, I agree.

I also really really really like my bees.  But I fear them, too.  As a new bee keeper, I'm afraid of killing them off en mass through some misguided management technique.  I might take too much honey off.  They might be over crowded and decide to swarm.  I could kill the queen with a poorly timed mite treatment.  What about wax moths?  Yikes! 
But I am really fascinated by them.  I could literally watch the hive for an hour.  I don't want to go on vacation for more than a week at a time in the summer in case they need me.  (Don't tell my husband!)
I've squished a fair number of them inadvertently as I move around different parts of the hive, and I've been stung.  Have your heard about "large local reaction" after being stung by an insect?  It can be quite spectacular.  As in I had to miss work, because my hand was so swollen that I didn't think I could do things like touch my finger to my thumb, grip a pencil, hold the steering wheel... 
All that being said, I don't think that they give two whoops about me.  They might hate me a bit when I crack the hive open.  When I feed them pollen/sugar they might enjoy or appreciate finding it miraculously in their hive?  What do bees feel?  They certainly get angry.  And I think they experience contentment when everything is right in the hive.  But I doubt they think that I have anything to with it.  

Three kinds of animals.  One human brain interacting with them.  But still, I care for them.  Differently, not equally.  If you put a gun to my head and wanted to make me choose one of them, I'd have to find a way to take the gun away from you, because I would not be able to choose who would live, and who would die.  Well, I'd let you have a few individual bees, but not the queen, because that would kill the hive.

How do you form your bonds with your pet?  Does it vary?  Have you loved one pet more than the others?  What does loving an animal mean to you?  Could you ever care for an unconventional pet?