A package is waiting for you on the doorstep. It's a large box, one you had been eagely awaiting. You drag its weight awkwardly over the threshold of the front door, and into your living room. The packing tape is no match for your excitement to get to the fluffy contents, and soon enough, an oversized dog bed flops out from its confines. The bed expands a little as it's freed, becoming a natural centerpiece to the room. It almost looks like a pet has made their home here, even though you're the only occupant—you can feel something in your brain activate with that thought.
You reach out and touch the fabric of your new bed. It's exquisitely soft; the short velvety fur is much nicer than typical sheets. It calls to you, saying you need to feel this texture with more of your body. You easily slide onto the bed, relaxing into its warm embrace. The soft foam inside gives just enough under your weight, making it effortless to let it envelop you. As you get up close to the fabric, you realize it has a slight smell to it, pleasant like a blanket just out of the dryer. Combined with the soft texture, and the gentle bedding underneath, the sensations are enough that they begin to occupy your mind with a warm haze. When you're sleepy in a dog bed this comfortable, exactly where you're meant to be, there's simply no room for other thoughts.
Some time has passed in your half-asleep state; a sunbeam has wandered across the floor and into the bed. You stir slightly, rubbing against the pillowy edge of the bed. Something drives you to roll onto your back, hands (paws? you aren't so sure anymore) tucked up in front of your chest. If there was some thought, the distraction of the sunbeam dismissed it before you could process what it was. With no warning, you feel a rushing sensation in your crotch, and moments later you feel the diaper taped around your waist warm and expand. As the warm stain spreads through the padding, making its way down to your butt, it's just second nature to clench your tummy and push. A warm mass quickly fills your seat, held firmly against you by the taut padding, which crinkles as it expands.
Your brain is fully entranced by sensations now. The dog bed is so comfortable with its soft fabric cradling you, and layered on top is the feeling of a thick, warm diaper between your legs, slightly moisty against your crotch and butt, and the heft in its seat which you can't help squishing slightly as you shift positions. There are smells too now, of course, but nothing you find unpleasant in your current state. It's only natural for an animal who's just soiled themself. The relief itself is a sensation too; the rush of going in your pants is followed by an intense satisfaction, and a little more sleepiness now that your pressing needs are met. As you snuggle in the dog bed, content in your full, soggy diaper, all these sensations build with no space for any other thought but one. You feel a deep sense of belonging: this is what you're meant to be, what you're meant to do. You're just a sleepy house pet with little concern for rules, enjoying your cozy bed. Content, your tail wags gently, and you begin to doze off once more.