I recently integrated my 2 8wk old Cuckoo Marans (1 hen, 1 Rooster) with my other 8 hens (7 are 1yr old, 1 is 2yrs old) and everything seemed to go well. They got picked on a bit but that only lasted maybe 2 days and there were no missing feathers or actual injuries. 2 days ago, one of my lovely children decided to give them "flying lessons". She somehow managed to get them to walk up the pitched roof of their coop where they perched on the top ridgeline and huddled there, until I got a ladder and rescued them (they were a good 9 feet off the ground!). Neither tried flying or getting off, basically just huddled up there and waited to be rescued. Now neither of them will leave the coop.
I free-range my chickens, so every morning I open the door and everyone comes barreling out but them and a broody hen. They've always been a bit cautious, last out the door, peering outside first but they've always gone out. Now they peek out the door and that's it. If I take them out of the coop they run right back inside and huddle together in a nesting box. Left alone they will wander around the coop, look out the windows and occasionally peek out the door but that's it. Food/water is in the coop as otherwise my stupid goat will break out of his pen and come gobble down their food.