"No"
"But Der look at his little face." Stiles holds the wiggling puppy even closer to Derek's face causing him to once again scrunch up his nose in an incredibly adorable manner.
"For the hundredth time, I'm allergic. No way that fur ball is coming into our house."
"You're not really allergic, it's just your werewolf urges telling you not to let another canine encroach on your territory." Stiles smirks up at him smugly and continues to whisper into the puppy's ear.
"Yeah, because I'm really going to be intimidated by that little thing." As if to prove his point Derek gives a half hearted growl and the puppy whimpers, hiding deeper in Stiles arms.
Derek takes a moment to just look at him. With his freckled face and hair all messy from the impromptu make out session that had occurred before coming in, Stiles was his normal endearing self. And all his. As idiotic as he knew it was, he hated the thought of having to share him, his attention. Even to a small harmless puppy that Stiles clearly already cared for. As if Stiles could hear what he was thinking he took a step closer, lovingly nudging Derek's shoulder with his head.
"It's not going to change anything. Sure we will have to feed him, take him out, close the door when we have sexy time. But other than that everything will be completely normal." He reached up and gave Derek a small kiss then brought the puppy in front of his face.
"Please take me home dad" Stiles used a overly high voice and peeked around the dog to give him an adorable smile. Derek had to admit, the dog was cute. And it's not like he would be the one taking care of it. Before he realized it he was nodding to Stiles, and he watched in amusement as he nearly ran to the checkout counter.
By the time they left the puppy was decked out in a bright red color with an obnoxious bow on it. They now owned 4 doggy outfits that Derek was convinced were considered animal cruelty. And Stiles had a big smile and bright eyes. Derek sighed and hooked an arm around his boyfriend. Life could be worse.