An SSBBW impregnating me, and then transferring her fat to me and fattening me to almost immobility. (As a revenge for fattening her sister & getting her pregnant)
I have this odd thing involving Willy Wonka's Fizzy Lifting Drink. The only thing is, in my fantasy it doesn't lift. The woman I give it to just gets fatter, and belches loudly and is content.