Every household has it's own dynamics and everyone develops habits to navigate them. The way I grew up, I think I developed special abilities with two, related roles:
I've become practiced at playing these, and seem to be able to recognise very quickly when others are too.
The care-taker is the child who magically understands your moods, needs and limitations, and moulds herself subtly to suit them. She might not be the child who does the dishes, he might leave a mess on the floor. But he will be the one who can sense you are sad, and hug you. He'll sometimes seem to know what you need. More often than not, she'll grow into a teenager who other people go to for advice. The one who can mentor younger children with ease.
The caretaker is the child who seems to see. The child who can sense.
The victim is the child who knows precisely how to use a situation - any situation. To generate attention, love, a cuddle, a lollipop, a day off school, a delayed exam. The victim is the one who can get off the hook by claiming extenuating circumstances. Often, these will be extenuating circumstances which everyone will understand. My Father is ill. My Father is dying. My Father this, my Mother that, my feet this, my head that. Often, the victim hides behind a pillar of competence. That's because he is the care-takers twin. He keeps her alive by allowing her to fall down in a heap. She keeps him alive by picking up the slack.
Together, they dance through the years, pulling and pushing this way and that, balancing the see-saw. They give power, they draw power. They expend energy, then they suck it back up.
Finally, when the abyss which was the 'extenuating circumstance' is finally over, it takes time and effort to overcome that mad dance, and move towards a better balance. I don't know if I can do it, but I know I want to try. Both roles are exhausting, and though life may be a stage, playing these roles is more puppet-dance than glorious stagecraft.
If you are caring for a child who has more responsibilities - practical or emotional - than 'normal' children, look for this. Tell me if what I've seen, looking back at myself, is also looking up at you. With a too-knowing smile, or an anguished and powerless grimace.