Hannah has an active imagination. She pretends to be just about anything. Cat, dog, cat that barks, hippo, pony, princess, pauper, mermaid, mouse, lamb, goat, baby, Diego, Alecia (Diego's sister), baby jaguar, elephant, dinosaur, planet, volcano, clam, walrus, any stinging bug, any of her cousins (which makes Matt and me our siblings and their spouses)... and that's just the ones I could remember off the top of my head.
What she's pretending to be can change after a few minutes or she could stay in character for hours, and you have to stay on top of it or you'll get answered with "I'm not _____, I'm ____". It's gotten so intense that she now tells us when she's "Hannah". She's only herself for two hours a day, tops.
I remember imagining so intensely when I was little that, as only little ones can do, I really felt I was whatever it was I was pretending to be. I can see that in Hannah. As an example, one day she was pretending to be one of her cousins which made me her aunt and her little sister became one of her cousin's siblings. We all get roped into this. As it happened, during this pretend stretch, her aunt called. When Hannah answered the phone and my sister-in-law said her name, Hannah looked at the phone with a funny look on her face, looked at me and said "It's *you*!" It was so hard not to laugh.
This pretending is interesting for Matt to watch. He says he never had much of an imagination as a child, so he doesn't understand what she's doing or why it's so important to her to be addressed as whatever or whoever she is in the moment. It's fun watching him play along with her now.