|“||The Shadow. The thing that rules the Empty.||”|
As it explained to Castiel, the Shadow controls the Empty and, that the dimension existed before God or the Darkness. When angels and demons die, they go to the Empty where they eternally slumber, allowing the Shadow to do the same. If even one of its charges is awake, the Shadow is awoken as well until the awakened being is asleep again or out of the Empty.
In The Big Empty, after the Seraph Castiel is awakened by Jack's telepathic call, the Shadow is awakened. It arose in the form of a pool of dark liquid inside the Empty after Castiel walked by before taking on a vague humanoid form. The Shadow followed Castiel as he made his way through the Empty, though he sensed the Shadow 's presence and called out to it. The Shadow took on Castiel's form to communicate with him directly, though it spoke with a distinct voice and accent. The Shadow identified itself as "just your friendly, neighborhood cosmic entity" and stated that it has taken on Castiel's form as its real form is too frightening.
The Shadow explained to Castiel that the Empty is what existed before everything, including God and Amara, adding that Castiel was "soaking in it." The Shadow told Castiel that every angel or demon that has ever died was in an eternal sleep inside the Empty, though but it was confused that Castiel was awake. According to the Shadow, "in all of forever", nothing has ever awakened inside the Empty as it mentioned its slumber being disturbed by his awakening. Castiel didn't know and suggested that the Winchesters must have made a deal, but the Shadow disbelieved this and stated that only it has power over the Empty with not even God having power there. The Shadow then put its hand to Castiel's forehead and painfully went through his memories in an attempt to find out what could have woken up Castiel. Afterwards, the Shadow explained to Castiel, who remained in pain, what he did and that it wanted Castiel back to sleep. It described Castiel being awake as a trapped gnat that was loudly buzzing in its head as Castiel realized from the Shadow's description that him being awake was painful for the Shadow. This was confirmed by the Shadow, stating that if Castiel could not sleep, then the Shadow could not sleep as well.
|“||If you can't sleep, I can't sleep. Yeah? And I like sleep. I need sleep.||”|
The Shadow insisted that it likes and needs sleep, causing Castiel to suggest that it get rid of him by sending Castiel back to Earth. The Shadow instead suggested that it throw Castiel so deep into the Empty that he could not bother it anymore, but Castiel recognized that the Shadow was bluffing. Castiel challenged that the Shadow's plan would not work as the Shadow would have already done it. The Shadow acknowledged that Castiel was right, but refused to send him back, telling Castiel that "it's not part of the deal." The Shadow stated that it has gone through all of Castiel's mind and knew everything there is about him and claimed that there was nothing back on Earth for Castiel. The Shadow grasped Castiel's head and painfully showed Castiel visions of his grace being stolen by Metatron, his death at the hands of Lucifer, the Escape of the Leviathans and Castiel returning the souls to Purgatory. The Shadow struck down Castiel, attempting to convince Castiel he was worthless so he would return to sleep. However, Castiel refused the entity's demands and declared that no matter what the Shadow does, he will fight it for eternity if he was not released. The Shadow angrily denied Castiel's demands as Castiel continued to demand for his release from the realm, staring down the Shadow while making his statement.
Castiel later awakened in a meadow on Earth and realized that the Shadow has complied and resurrected him as Castiel demanded.
In Tombstone, the resurrected Castiel tells the Winchesters that he annoyed an "ancient cosmic being" so much that it sent him back.
In Byzantium, following the death of the Nephilim Jack, the Shadow invades Heaven to get Jack's soul, believing him to belong to the Empty because of the boy's angel side by possessing and incapacitating all of the angels. The Shadow easily defeated all defenses put up and chased Jack when he emerged from his Heaven but he managed to elude it. Jack later told Kelly Kline of what is after him and she hides him from it.
When Castiel entered Heaven in search of Jack's soul, the Shadow, possessing the angel Duma, accompanied Castiel in his search. The Shadow overwhelmed and possessed Naomi when she reminded Castiel of it and tried to convince him to help them turn Jack over to it.
As Castiel met with Jack and Kelly Kline, he told them of the Shadow and its intentions. The Shadow overheard their plans to resurrect Jack, before it revealed itself and attacked in an effort to take Jack to the Empty, easily defeating Castiel and Kelly's attempts to protect Jack. Recognizing that the Shadow wanted to get back at him, Castiel offered to trade himself to it for Jack immediately, pointing out that otherwise, it would have to wait years, perhaps eons for Castiel to die again. The Shadow accepted Castiel's deal, but decided to wait until Castiel was truly happy to collect on it since it wanted his end to be painful. After making the deal, the Shadow left Heaven and returned to the Empty, restoring the angels back to normal.
|“||I'm just your friendly neighborhood Cosmic Entity.||”|
When this didn't work, it attacked him out of frustration and called him worthless, which proved unsuccessful. The Shadow was very angry at Castiel's defiant attitude but finally complied in annoyance, to resurrect Castiel to be able to return to its slumber. This shows that the Shadow is somewhat impatient.
|“||I want you to suffer.||”|
— The Shadow to Castiel in Byzantium
During its attack on Heaven, more about the Shadow is revealed. The Shadow is shown to be impulsive, mentally unstable, possessive, invasive, vindictive and sadistic. It views angels' and demon's essences as its material possessions, and is wiling to go to great lengths to claim them. It targeted Castiel's nephew Jack at least partly for this reason. Naomi also worded this by stating that the Shadow considered Jack as its property, or because of his indirect role in waking it. Its impatience and mentally unstable psychology is shown when it aggressively reacts to Castiel interrupting it.
It is also proven to be relentless in its goals as seen when it invaded Heaven and violently attacked the remaining angels in an effort to claim Jack and according to Naomi, threatened that Heaven would fall if they do not hand Jack over to it.
The Shadow's sadism was proven when after Castiel offered himself in Jack's place: the Shadow quickly accepted the bargain, but it chose to wait until Castiel was truly happy to collect on their deal in order to make him suffer to complete its vengeance.
Powers and Abilities
|“||I'm the only one that has any pull here. Not Heaven, not Hell, not G-O-D himself.||”|
- Nigh-Omnipotence (At least within the Empty) - The Shadow has the power to do practically anything and has complete control over the Empty. The Shadow claims that not even God has strings on the Empty and all within it. However, the Shadow lacks the ability to force something that has awakened in the Empty back to sleep and must either convince them to return to sleep on their own or expel them.
- Nigh-Omniscience - The Shadow has a certain level of cosmic awareness: it knows about the world and what happened before its creation, as it knew about The Darkness and her human name. Despite this, even it couldn't figure out why Castiel had awoke in what it considers all of forever. It was also able to detect Jack's death and knew to find his soul in Heaven. While possessing Duma, the Shadow was able to perfectly mimic her behavorial mannerisms and personality. Even Castiel didn't notice that Duma was possessed, until the Shadow revealed itself.
- Shapeshifting - Due to its terrifying true form, the Shadow takes on the form of the being it is speaking to, though it speaks with a distinct voice instead of mimicking the being's voice. In The Empty, it changed from its true form to Castiel's visage when speaking to him and before pursuing him, it changed from a puddle of black ooze and took on a vague humanoid form to walk around The Empty. When possessing Duma, the Shadow briefly altered the appearance of her face to that of it's true face before reverting back to Duma's appearance .
- Invulnerability - It cannot be killed or harmed by any known weapon.
- Immortality - It has been around for a very long time, since at least before angels, and is immune to aging and disease.
- Super Strength - The Shadow was able to effortlessly overpower and beat Castiel. When it attacked Heaven, the Shadow effortlessly defeated all of the remaining angels. The Shadow was also able to overpower Castiel and Kelly, and strangled Jack to the point that he was briefly unconscious with no effort.
- Telepathy - In order to learn more about Castiel, the Shadow painfully dug through his memories. The Shadow later used this power to show him some of his most painful memories in an effort to convince Castiel that he was worthless and should go back to sleep.
- Resurrection - The Shadow was able to resurrect Castiel, returning him to Earth in the process.
- Reality Warping - The Shadow is able to create matter out of nothing as it fully rebuilt Castiel's vessel, which was previously burned and destroyed with no visible damage leftover. When it attacked Heaven, the Shadow broke open all of the gates, even the ones sealed by Metatron's unbreakable spell.
- Possession - While in Heaven, the Shadow was able to possess all of the surviving angels, essentially consuming them as seen with Naomi and Duma and turning the angels into its vessels. When the Shadow left their bodies, Duma at least had no memory of the experience but the angels were left otherwise unharmed.
- Telekinesis - The Shadow was able to stop Jack by raising its hand towards him.
- Flight - After leaving Duma's Vessel, the Shadow's true form flew into an air vent in a house within Kelly's Heaven before returning to The Empty.
Although it is the ruler of the Empty, it has a few weaknesses as well.
- Awakening of The Empty Inhabitants - As long as the inhabitants of the Empty sleep, so does The Shadow itself. However, if even a single inhabitant is awake, it also wakes up the Shadow from its sleep. Furthermore, having waking inhabitants in the Empty causes it pain.
- Sleep Deprivation - Being in deep slumber since before all existence, the Shadow can be severely disturbed if it cannot rest. Castiel claimed, while he cannot beat the Shadow, he can stay awake to lay pressure to it.
- The Shadow claimed that its true form induces complete insanity, even to angels.
- The Shadow had stated God has no power over The Empty but the latter has been able to resurrect Castiel multiple times. This brings up the question as to how he did so in the past.
- The Shadow's state of eternal sleep and maddening appearance shares similarlies to two beings in Lovecraft Horror Stories, specifically Azathoth and the Nameless Mist. Azathoth represents the Entity's madness-inducing state, eternal sleep, and existing outside creation. The Nameless Mist represents the initial appearance of the Entity.
- The Shadow also bears a strong resemblance to Chaos, a primordial deity of void and nothingness in Greek mythology, which was described as a dark void predating the creation of the universe and the cosmos.