In A Great and Terrible Beauty, it might seem like the deer represents too many different things to be a reliable symbol—after all, it shows up in dreams and reality, and with different characters—but each time we see a deer in this book, it clues us into the same sort of thing: the fundamental nature of whomever is interacting with it. And this makes sense, because deer show up in… drum roll please… nature. And so in this book, they show us people's nature. Got it? Good.
The first big moment with a deer is in Gemma's dream of her mother:
It's a deer I'm chasing, its milky brown flesh peeking through trees like the taunts of a will-o'-the-wisp. […] Fingers graze the fur and it's no longer a deer but my mother's blue dress. (10.13)
Here the deer represents Gemma's search for meaning and understanding about what is happening to her and what happened to her mother (that's why its fur turns into her mother's dress at the end). Gemma is haunted by her mother's murder and the strange visions she has, and the deer lets us know these mysteries rock Gemma to her core. The answers she seeks are key to who she is in the world and how she will continue to be in it, and the essentialness of this information—that it has to do with her very nature—is made clear through the deer.
The deer clues us into some pretty cool stuff about Gemma in the above passage, but this isn't always the case. So when Gemma's friends brutally murder a deer out of desperation to gain power for themselves, we understand that there is a nastiness at the ringleader, Felicity's, core that is a fundamental part of her, and that Ann—who follows along with the killing, though not nearly so eagerly as Felicity—is so incapable of asserting herself that she can be led to do terrible things in this world.
On the flip side, when Kartik buries the deer, and feels immense pity for the animal, we are clued into the kindness that blooms in his core—and since we don't know a whole lot about him, this insight is particularly meaningful and helpful for us as readers.
Finally, at the very end of the book, a deer appears to Gemma during her reflection:
I see her in the dry crackle of leaves. A deer. She spies me and bolts through the trees. I run after her, not really giving chase. (39.14)
The deer bolts—a motion that exudes excitement, energy, and vitality—and when it does, and Gemma follows after it, we know that her excitement, energy, and vitality are in tact.
Are there other moments involving a deer in the book? What do they tell you about the nature of the characters they interact with?