Had a messed up Raggedy Ann angst idea, just bear with me for this, ok?
So, you know of the whole "possessed doll" trope, right? And I learned that the creator of the Raggedy Ann and Andy dolls (and books), Johnny Gruelle, based Marcella in the stories after his own daughter, and the dolls always made him think of Marcella.
Because Marcella died when she was thirteen. I don't exactly know if this is true or not, but I heard that she died due to an unprescribed vaccine that got infected.
Now, back to Raggedy Ann herself. I imagine that Ann would talk about Marcella constantly and reminisce about her adventures with her, until saying that one day, Marcella "Never came home".
But she doesn't know those memories are not hers. They are Marcella's. And what Raggedy Ann doesn't realize is that she is Marcella. A girl who departed too early, now living a second life, traped in the little doll body of Raggedy Ann.
On top of this, I imagine that Ann has a terrible fear of needles, although she never knew why. It would be the kind of thing that seemed funny and ironic at first, but eventually, you realize why.
It's the thing that killed her.