Looking for any and all stories where pets are involved, to any varying degree.

I will also be ok if it's someone who has turned into an animal and pretends to be a pet until they are found out.

Dogs, cats, magical animals, you name it.

Thanks in advance.

Hi,

Here are the ones I have in mind:

Mortal Allies series by Passion4Spike on EF, ff.net and AO3.

Summary: What happens when mortal enemies call a truce to save the world? They become mortal allies. Begins with the truce between Buffy and Spike during Season 2, Becoming. Take an unsouled, unchipped vampire named Spike, a mystical guardian dog named Spike, and a Slayer who loves the latter and hates the former, toss together and shake vigorously -- what could possibly go wrong? I don't have too many specific plans for this series other than to keep throwing them back together, making them work together as reluctant allies, generally in short-ish installments.

Peaches & Cream by MissLuci on EF and AO3.

Summary: «Every night I save you.»  -  In this AU, he does.
Buffy and Spike begin their relationship at the end of Season 5.  A few very steamy months later, things are getting serious and Buffy asks Spike to move in.  Soon afterwards, much to Spike's dismay, another much smaller addition joins the residents of 1630 Revello Drive.  Spike becomes captivated by her charms as a third Summers girl wraps the sensitive vampire around her little finger... erm... tail.  
 
Much Spuffiness abounds in this (mostly) Fluffy, Smutty Season Six.

Civilized Monster by Axell on EF.

Summary: What's the definition of a monster?
You can check the dictionary or judge yourself.  

Meow by CheekyKitten WIP on EF.

Summary: Spike is great at pissing people off and typically it results in some of the best fights of his life, but this time, and he's not really sure how... he's been turned into something... something small, helpless and ... he really hates to admit it, adorable!
So who do you go to when you're helpless? Slayer's not a bad option!

Ruff Times by othellia on EF and AO3.

Summary: Set in an AU summer after S5 where Buffy managed to beat Glory without sacrificing herself. The divine threat is gone, but daily struggles never stop. With both slaying and a new job, Buffy doesn't have the energy to figure out Spike's new role in her life... until a spell ripples through Sunnydale, turning the local demon population into dogs.

What Happens In Quarantine... by bewildered on EF and AO3.

Summary: Complete! There's a virus loose in Sunnydale, deadly to vampires and humans alike, and the whole town is on lockdown. Normally Buffy would welcome a little time away from it all — but did she have to be quarantined with Spike?!? Sparks fly and tempers flare, and as days turn to weeks and months, it's just a matter of time before something goes terribly, horribly wrong... Fortunately, what happens in quarantine stays in quarantine, right?

I'll edit if I come up with more stories.

https://archiveofourown.org/works/28878768

SummerFrost has a magnificent story where Spike adopts a cat. It's bloody brilliant. Also bittersweet.

flow

And some more:

Little Ball of Fur by Feanix88

 Summary: Angelus never returned from Acathla's Hell Dimension and The First still lies dormant. Feeling the loss of her sire Drusilla does more than just that Chaos Demon in Brazil, when Spike returns to his black beauty following 'Lover's Walk'.
It's Christmas, and after weeks of jumping trains, and avoiding Demon Poker Tables, Spike arrives back in Sunnydale; in his worse state yet.

Free to a Good Home by though_you_try WIP

Summary: Spike realizes a kitten can be many things, from annoyance to delight to thinly veiled metaphor. Buffy vehemently insists she doesn't want any of those things anywhere near her life.
The kitten has other plans. But how many relationships can one tiny cat fix?

Something Furry This Way Comes by Mefiant On TSR, ff.net and the Bloodshedverse.

Summary:
A fluffy interlude set somewhere around early S6 Spike and Buffy are NOT together, and no mention of Buffy's death is made. Spike makes his animal magnetism known, but not in the usual way.

Winter Wonder Hell by Synefred 

Summary:
Shaken by the memories that flooded through him when his soul was returned, Angel took off into the night, leaving Buffy and an ever growing portal to a hell dimension behind him. With no other choice, Buffy stabbed Spike, condemning him to an eternity in Hell. The only problem was that as he was sucked in, he pulled Buffy in with him. 
 
Buffy always expected Hell to be full of fire and brimstone, but now she is trapped in a twilight realm, where the cold bites and the darkness waits. As she and Spike battle their new reality, and each other, the lingering question is, what will they do when the snow finally falls?

Faster Pussycat, Kill! Kill! by Minx DeLovely On TSR, EF and AO3.

Summary: What if Buffy had chosen a leopard costume instead of the guise of a noblewoman on the Halloween Ethan turned everyone into their disguises?

Longer, Then Forever by Demonica Mills

Summary: What if Buffy had gone to hell when she jumped in Glory's portal?

Light Blue by Spuffy93

Summary: Spike, Buffy, and Harmony are talking outside the fraternity house when a strange demon appears and attacks everyone without distinction. Harmony escapes as Spike and Buffy stay to fight the demon together. They win, but then a bright blue light engulfs them. Things as they know it will change forever.