Ask if you can see Sarah dressed up.

"If Sarah wants me to know this then I guess she wants to be able to be dressed up while I'm around." You reason.

"Yes." Tanya says "She wants to be able to be herself around you."

"Would she show me now?" You ask. "I want to understand what this is all about."

"I'll go ask" Tanya gives you the impression that she already knows the answer is yes. "Wait here."

She leaves and quickly returns with Sarah who smiles nervously at you.

Tanya immediately pulls Sarah's dress off over her head.

"Sorry." You say, turning away. "I thought I was meant to wait here. I'll give you some privacy."

"Don't worry." Tanya says. "Babies aren't self-conscious."

You turn back to see Sarah standing in just her bra and a puffy white diaper. You hadn't quite believed Tanya until now but seeing Sarah standing there in a diaper finally makes it real.

As you process this, Tanya unclips Sarah's bra and helps her out of it. This is the first time you've seen her breasts. You had imagined it many times but in none of your fantasies was she wearing a diaper. Of course, that doesn't stop your dick from growing hard in your pants.

Tanya goes to the wardrobe and retrieves pink footed sleeper with little teddybears printed all over it. She holds it out for Sarah to step into and then pulls it up her body. She helps Sarah find the sleeves and put her arms through them before zipping her into the babyish outfit. Finally she clips a pacifier to it, hanging from a plastic chain.