That's almost like R
That's similar to Rosie and the twin, except the twin is only 2 weeks older than the keets and ran from her. But she does have a keen desire to be near & guard the keets. At 1st I thought she was trying to blend in, but as I said, she's taken on a Nanny role. After helping search for the wandering keet the other day, Rosie seems to have tentatively accepted her as such. She even left some w/the twin yesterday when she decided she was done dust bathing & 5 of them didn't notice that the others had left.
There are various theories about their habits. One is that one pair is the Alpha,the rest subordinates who may or may not brood but will guard the A female while on the nest. I saw this play out last yr- the two jumbos had nests and the rest divided & guarded. When Lucy & her nest were taken, they all moved to guard Rosie. - male & female. I didn't let her cont on the nest,so no idea how it would have panned out.
This yr, Bella sat w/her until she went missing, & then ofcourse Nugget stepped in. PJ took perimeter, when he thought of it.
We know the boys took up parenting. The triplets stayed away from them,the twins tried to blend until the massacre.
Going any further would be conjecture. SO has had the trauma- trying to fit in or replace or developed that desire to defend?

Rosie is definitely more sensitive to loss than the others were. Remember she kept going back to Lucy's nest site & calling. I can't say I expected or paid much attention to her reaction to others in the past, but the field incident definitely affected her. Her whole demeanor was that of an old woman hunched over & beaten down by life. As I've said, she's coming out of it now, but for awhile I was sure the only thing keeping her going was her responsibility to the keets.