The fantasy in my case is from the opposite end of the stick.
I would love to have a partner who wants to be the little one, someone whom I can put in nappies, change, bath, cook for and feed, play games with and take out to cool places, reprimand when their naughty (maybe even with a spanking), sew cute outfits for and just generally love and care for them as a daddy.
While I would prefer it to be a girl I don't really mind either way.
I would however also like it if it was not an "always on" little side as it would be nice to have someone I could talk about and do grown up things with too (and no I don't just mean sex), and if they were willing to change my nappies and (rarely) switch so I could have fun as a little too that's great.
Well that's one fantasy there are two others that I have (and regularly imagine/dream about) that are similar but I know is probably not going to happen...
The first is owning a real ABDL nursery, I'm not talking about having a home where people can visit 1 or 2 at a time for a few hours play. I mean having like a whole decent sized building like an actual real nursery with lots of varied toys, games, books, activities, clothing etc. a large enclosed and private garden with a big sandpit, swings, slide, climbing frames etc.
Somewhere with "bedrooms" upstairs so people can stay for a few nights, imagine like a B&B with many small bedrooms upstairs (perhaps a dorm style too with lots of cots or childish beds) but the whole ground floor is playrooms and a dining hall including high chairs. it would have to be large enough that could have say 30+ people comfortably at once for play (though maybe only able to sleep 10-15).
ABDL's could pay a one off fee to visit for a day or register with me for a small annual fee which would allow them to pop in to visit at any time in the open hours of the day (say 9AM to 7PM) to play and be treated as whatever age little they like. They could also could pay a one off fee (cheaper if the are registered) to stay overnight for as many nights as they like and have a full 24/7 experience.
The final fantasy that is similar to the last is that I would love to have the cash to buy a small island somewhere off the coast. It really doesn't need to be that big but large enough to have some renewable energy (wind/coastal power), be relatively self sufficient (some farming, water treatment, comms relay etc.) and have space for maybe a couple dozen houses and a moderately sized hotel. Having a small beach with a dock and potentially a small airstrip for lighter aircraft to get people to and from the mainland for supplies/visits.
The idea being I'd invite a bunch of ABDL folk to come and live there, preferably with a variety of skills so that we could run and maintain any equipment/farms etc. to keep it mostly self sufficient. I could open the hotel up for visitors (probably mostly ABDL folk looking for a vacation where they can freely indulge their ABDL desires) in order to generate some income and some of the islanders may be able to find paid work that can be done remotely/online so that we are able to purchase supplies when needed and everyone could live an open ABDL lifestyle.