Sally Jackson has watched her son through war and peace, love and hate, darkness and light. She stands by him through it all, because it is family before anything else. The loss of her own parents has taught her.
They are all family, his friends and cousins and everyone else. They are Percy's family, so they are hers too.
So she welcomes them all in with a loving smile. She tends to their wounds and feeds them and gives them the love they starve for.
Family is something she has once lost, and she will never let it go again.