All baby poultry seem to be very nice to each other at the early stages.Fortunatley, it is possible to keep ducks with hens, ducks are very docile birds and they seem to be very nice. I would recommend you get a Pekin duck, their one of the most docile and tame duck species out there; they are also very enjoyable as ducklings. The only thing Is I'd get only get one duckling, if you get a few ducklings and they lived with your hen your chick might be bullied because she is different. One duck and one chicken would balance everything out. And yes chickens and ducks can live in he same coop, although notice that ducks like to swim in whatever they can fit themselves in, so a water bowl wouldn't be good for drinking source, so I would recommend a water feeder so both birds can have equal water supply. One more thing, make sure you have a spacious and appropriate coop so each bird is healthy and happy! I don't think a male would dominate over a hen considering that male ducks are actually more docile then female ducks.
Best of luck!
Edited by sunshine ducky - 6/8/16 at 1:52am