This is the routine now.
Take the chick out of her coop in the evening and put her in the cage in the main coop. It's next to the roost and at the same height, so she gets a feel for roosting with the flock. She used to run and scream when I tried to catch her in her coop, but though she still does that to an extent, she jumped onto my hand last night and stayed there. I hold her and comfort her inside the main coop while all of the others watch as she cheeps. Last night the mother actually let out some sort of verbal acknowledgment of her.
In the morning I let her go with the others to feed them. She scrambles around a bit then heads towards her run. This morning she was a bit more curious about things outside before going inside. As she gets bigger, I'll leave the gate to her run open, and she can do what she wants.
I wish she had another chick companion, but she seems pretty content. I conduct flock feeds outside her pen 2-3 times a day so that she gets some company, and tell her that they all came by to see her.