"A cup of tea, Charlie? You've had a long trip!" I pat Charlie's rainbow-colored tail and set a plastic Peppa Pig plate piled high with rainbow cakes in front of her. Then I serve tea. Charlie takes a sip, and so do I. 

Charlie's just come back from Rainbow Land—that's where we're both from—and she's telling me about her adventures there. How she went to the magic garden where we used to grow our magic beans. The ones that give you wings to fly. That's how she got back here to me. She ate some of the beans to grow huge new wings and took off. On the first trip, when we first left Rainbow Land together, I rode on her back. And let me tell you, that was a wild ride.

I'm laughing and chewing on a chocolate sparkle cookie that glows in the dark when a voice interrupts us. I stick out my lower lip and knit my brow like I usually do when I hear this voice.

"Gertie, what are you babbling about, and who are you talking to?" My thirteen-year-old sister, Riley. I don't understand why she always says "babbling" because I don't babble. I speak like the perfect princess that I am. Did I mention I'm a princess? A real one. With a real castle.

"Don't even tell me you're talking to that stupid unicorn again—Mom, Gertie's sitting in one of your boxes, talking to her imaginary friend, and ewww, she's chewing on a piece of old eraser. Gross! It's black, and I think it's rotting!" 

Then she does the worst thing: She wrangles the chocolate sparkle cookie out of my mouth, grabs me by the arm, and tells me to leave my castle and my unicorn. I start to cry, major waterworks so that Mamma will hear. Through the tears, I can just make out Riley's scowl as Mamma tells her erasers don't rot, then says something about imagination being the blah, blah for kids and the imaginary is all blah, blah part of that—I don't understand.

And I don't understand why she's even talking about imagination and imaginary. What's that got to do with me?

Mamma wipes my runny nose, kisses me on the head, and escorts me back into my castle.

"Stupid box," Riley mutters, but I ignore her.

"Did you take your new medication, Riley?" Mamma asks.

I peer out of my castle. My sister's still doing the sour face.

"Yeah, an hour ago," she grumbles.

"Go lie down in the living room. Remember, the doctors said the meds might cause some hallucinations so best if you rest... I have to run out on an errand, but I'll be back in less than a half hour, OK?"

Mamma puts an arm around Riley, and they both disappear into the living room. I'm back in the castle, serving tea to Charlie, who loves tea more than anyone I know. Especially bubble gum flavored.

And then I hear a shriek. Charlie looks scared, but I tell her everything's OK. Then I pop my head out the door and listen.

Riley's saying, "this can't be real, this can't be real." Over and over again.

"Wait here, Charlie. I'll be right back." I pat her on the wing, then race around the corner, tripping over my royal gown as I go.

When I see Riley, I stop. She looks more scared than Charlie did. I'm not used to this. Usually, she just looks grumpy.

"Go away, Gertie," she says. But I don't move. I need to be in on the action. So I fold my arms across my chest and glare at her.

"Won't leave," I say. "I wanna know the secret."

Her grumpy face is back. "OK fine. The Seven Dwarves, as in Snow White's pals, are over there, right behind the piano. But it's not real. It's this medicine that makes me see weird stuff, that's all."

I turn and clap my hands with delight. I see them. Then I jump up and down and skip across the room. I grab Happy by the hands, and we dance around. Bashful sits at the piano and plays "Whistle While You Work."

"Wait a minute," Riley says. "No. This can't be real. Gertie, get back over here and stop pretending!"

"It's not pretend! But they can't stay long—Happy just told me they have to go see Snow White. To save her! I'll walk to the door with them and so will Charlie."

Charlie's not scared anymore. She trotted over a minute ago and now is licking my face. She's got bubble gum breath. The dwarves kiss my hand as they walk out the door one by one. They promise to say "hi" to Snow White for me.

"Look, even though I did see them walk to the door with you, all of that was a hallucination, Gertie." Riley's lying on the couch as she says this, and I'm standing over her. She looks kind of greenish, and she's staring at the ceiling.

I shrug and skip back to my castle.

Mamma comes home a few minutes later, and I peek around the corner. She's holding a tiny hat in her hand. It's Happy's. I recognize it. I look at Riley, and all of a sudden, she looks even greener. I run to my doctor's kit, grab some pink pills, and rush them over to her. If anyone can heal her, it's me. I don't know if I mentioned it, but I'm not just a princess. I'm a doctor too.