Mark leans forward and gives Cal a long lick on the cheek.
Cal smiles and pushes Mark back, "Hey, not in front of my sister."
Mark smiles, "Your my bitch now Cal."
Cal nods, "I like how that sounds. And I told Katy most of what happened last night. Show her yours."
Mark unzips his jeans, and pulls down his boxers to show the well sized canine balls and sheath.
"Cal was a rottweiler in canine form." beams a proud Cal.
"Well, you were a German Shepard" responds Mark.
"I have to fly back at the end of the week, so you two need to make sure this is what you want. Remember, you have our parents and Mark's parents to consider." warns Katy.
Mark pulls up his jeans and zips up, and walks over to Katy and whispers, "How would you like to ride on the Mark Pole?"
Katy pushes Mark back, "Not unless you do us both and Buster." as she points over to her brother.
Mark found the idea of anal sex with a male dog arousing. "Your on."
Katy said, "I'd rather be canine for this, so let me change and we can all meet up in my room in a few minutes." Katy looked over to her brother, "Do you still have them?"
Cal shook his head, "They are under your pillow."
"Give me five minutes, and come on in." says Katy, and she smiled while she walked back to her bedroom.
Mark turns to Cal, "Damn your sister is kinky, just like you."
Cal walks over to Mark and hugs him, and Mark returns the hug. Mark reassures his mate, "Don't worry buddy, I will take care of us." Cal and Mark embrace in a passionate kiss for a few moments, before separating, staring into each other's eyes. Mark nods and his hands reach down to unzip his jeans, while Cal helps with the rest. Soon, Cal's mouth is suckling on Mark's rock hard pink shaft. Cal is rewarded with a mouthful of canine spunk after a good minute of the best blowjob Mark has ever had. As Mark strokes the hair on Cal's head in the afterglow of his orgasm, "We had better save some for your sister."
In both Mark's and Cal's minds, they were deeply in love with each other. The collar's lasting effect to change their inhibitions, and their sense of loyalty to each other. Being best friends served to reinforce the strong bond between the two. Mark pushed Cal off his cock, and pulled him up, as they walked back to Katy's room. Mark opened the door, as Katy was in mid-change, her naked body quickly becoming furred while her face was fast becoming canine. Cal leaned into Mark as he watched his sister.