Twilight: Now Spike, I need you to bring me this book and... Spike: Uh.... why don't you get it yourself.... you know.... by magic? Twilight: Spike! I know it upsets you, but.. Spike: Seriously? You got magic, you even have wings now! Could you explain me why I should get it myself and not you? Twilight: Uh.... because you are my assistant and... Spike: I know that! *cross arms* I want a real reason. Now. Twilight: *sigh* Fine. *she levitated the book from the shelf with her magic and trotted away, a frown in her face* Spike: See? It's much easier that way. *looks around* Uh... now... what do I do. Twilight stopped and look in the direction of Spike. She levitated all the books of the portion of the library she got her book and put them all on the ground. Spike: Hey! What are you doing? Twilight: I was just trying earlier to make you busy at work. Now that you seem bored, put all these books in alphabetical order, after cleaning their covers. Spike: What? But you just wanted this book... Twilight: Right. But after what you said, you made me realized that I should give you slack on that task. Spike: You mean? Twilight: *grin* *she put all the books back at their places with a leviation spell* I was teasing you. *giggle* Spike: Humph! Twilight: Come on, Spike. You know very well how important you are to me. Spike: Yeah. You couldn't have the time to clean the place between trips with your friends. Twilight: Uh... true. But it doesn't mean I don't want you to come... Spike: The place would be full of torn scrolls and papers... and empty ink wells... Twilight: Uh.... yeah... Spike: And you wouldn't stop eating daisy sandw- Twilight: I got it, Spike. That's why you are my assistant.... Spike: And the assistant wants a gem because you hurt his feelings earlier... Twilight: Don't push it. *trots away* Spike: BTW, what are you working on anyway? Twilight: Huh? Oh! A spell..... a spell on how to make a too needy assistant disapear.... Spike: Uh.... Twilight grinned. Spike: Do you think it works with a too needy princess pony? Twilight stopped with a shocked face and stared at Spike with a frown.
But, behind that book, is a SURPRISE GIFT FOR SPIKE BECAUSE IT'S HIS BIRTHDAY!
That's the only reason I could imagine Twilight being a jerk and making her super short #1 assistant get a book from the top shelf when she has both the magical ability to levitate almost an entire library's worth of books or she could fly up and get it herself. She's not even currently indisposed or anything.
Jeez, it's not like she has her hooves full with other things. She could easily use her magic to bring that book down, or even fly up to it, but nope, she has to send her little dragon assistant up there. At least give Spike a ladder!