Trauma
As a story about two women who encounter an inexplicable creature they spend the rest of their lives trying to make sense of, "The Thing in the Forest" is centered on the theme of trauma. The story's inciting incident involves Penny and Primrose being evacuated from London to escape the dangers of the German bombing of the city. The evacuation amounts to a traumatic severance from the lives the girls have always known. War with its attendant horrors replaces their regular lives, bringing confusion, despair, deprivation, and the deaths of both their fathers. All of this suffering is encapsulated in the Thing, a monstrous amalgam of misery and detritus. Penny and Primrose both respond to the war's disruption to their lives with emotional repression and isolation. When they meet as adults, both childless and unmarried, the women agree that the shock of seeing the Thing in the forest "finished them off." The traumatic encounter with the inexplicable monster doomed them to lives spent obsessing over what the creature was and why they had to see it. In this way, the creature represents the emotional trauma brought about by the war—a trauma neither woman has moved past.
Loss of Innocence
Another of the story's major themes is the loss of innocence that results from Penny's and Primrose's encounter with the Thing. With the line "There were once two girls," Byatt begins the story in the register of a fairytale, emphasizing the innocence of the protagonists. However, that innocence is soon complicated by the historical context in which the story is set. Oblivious to the danger of staying in London, both girls are unsure what to make of the evacuation, and both worry it may be a punishment. Byatt again emphasizes their innocence by commenting on how they interpret the blacked-out station names not as a wartime precaution to confuse an invading army but as an erasure meant to prevent them from finding their way home. After establishing the girls' innocence, Byatt introduces the Thing and its undeniable, revolting presence. Upon seeing it, the girls shake in terror but say nothing, not knowing what to make of the incursion on their lives. Decades later, the women discuss how the moment marked a turning point for them both. Witnessing the Thing—which represents the misery of living through the war—was akin to having lost their innocent view of the world and humanity. Ultimately, neither woman can unsee what they have seen, just as they can't retrieve the innocence they lost that day.
The Unreal
The unreal—and how to make sense of it—is another dominant theme in "The Thing in the Forest." Byatt explores the theme through Penny and Primrose's encounter with the Thing, which amounts to an encounter with an inexplicable force that is nearly impossible to incorporate into their understandings of life. As an invented creature composed of the detritus of daily life and embodying humanity's suffering, the Thing is made of familiar components; however, those components come together in a package that is decidedly unreal. The unreal Thing's existence is such a shocking disruption that Penny and Primrose both spend the rest of their lives thinking about it, their minds scrambling to contextualize the creature in what they know of reality. As an adult, Penny tells Primrose that she thinks the Thing is "more real than we are," and that it entered their world during the "very bad time" of WWII. Although her explanation may sound paradoxical, Penny's opinion that the creature is "more real" implies that she believes stable reality itself is an illusion. The creature, although a fantasy, is more real because it represents the true suffering and devastation undergirding humanity. Ultimately, this glimpse of the unreal prevents both women from taking part in regular reality ever again. Instead, they live on the threshold between the real and unreal, forever divided.
Unprocessed Grief
Unprocessed grief is a key theme to understanding "The Thing in the Forest." As young girls living through a time of great social upheaval, Penny and Primrose suffer several losses as a result of the Second World War. The war's incursion on their lives means the girls and their families contend with food rationing, economic instability, educational interruptions, constant fear of being killed by the enemy, sleeping in inadequate bomb shelters, and the deaths of both family's patriarchs. However, the entire country is enduring similar devastation, leading to a widespread sense of resignation as everyone waits for the war to end and things to return to normal. In a social milieu where everyone is avoiding the pain and vulnerability that comes with grief, both characters respond to their mounting misfortunes with emotional repression. Byatt conveys this tendency through the fact that neither woman has ever talked about the Thing in the forest to anyone, because to do so would mean processing the misery the Thing represents. Even when they have the opportunity to relate to each other about the disruptive experience, Penny and Primrose mutually decide to skip the dinner they agreed to. In doing so, they avoid having to acknowledge the grief they have been repressing in the decades since the war.
