Could Sam and God's matching bullet wounds in Sam and Dean rumbled Chuck's ruse, Sam shot a bullet at Earth's Lord and Savior, hitting him squarely in the shoulder. Strangely, Sam recoiled and winced as if he had been struck in exactly the same place.
The toll of that injury is now becoming clear, as both God and Sam Winchester struggle with their mirrored wounds in Supernatural season 15. Sam is physically troubled with the pain caused by the circular, blackened contusion and even the angelic magic of Castiel was unable to make things better. Instead, Castiel claimed to have never felt an energy like it. While Sam may be hampered by a sore shoulder, God appears to be hampered to a far graver extent. The Equalizer has chipped away part of God's powers, leaving him unable to traverse universes at will. Trapped on Earth and not firing on all cylinders, God is frustrated, and a frustrated God is not good news for the Winchester brothers.
But what could these matching wounds mean as Supernatural barrels towards its final ever episode? Showrunner, Andrew Dabb, has described the injuries as a "string" connecting the two tin cans that are God and Sam Winchester, while also hinting that the link will have both advantages and disadvantages for the brothers. The pros of the situation are clear - Sam and Dean have a direct line to their arch enemy if they can figure out how to use it. However, it's the drawbacks that could play into Supernatural's finale and Sam's teased villain turn.
The Equalizer doesn't just attack a person's body but their soul, and Supernatural has explored previously how Sam turned cold and heartless when lacking in the soul department. The effects might be slower and less drastic when only a piece of Sam is missing, but it still opens the door for evil Sam, as glimpsed in several visions throughout season 15, to make an appearance. More speculatively, the wound's black outline looks distinctly like some kind of virus. If the Equalizer's damage can sap away God's power, and an angel's power is directly connected to their soul, Sam Winchester's soul could be slowly ebbing away with each episode. This would perhaps explain his evident anger at ungrateful civilians in "Atomic Monsters."
Secondly, while the bullet wound might provide the Winchesters with an insight into what God has up his sleeve, it could also give the deity an opportunity to corrupt Sam. The evil version of Sam that appeared previously in a dream sequence appeared to possess incredible power, brought on by his demon-infused blood. Sam's demonic psychic abilities have been dormant for the better part of ten seasons, and even when the youngest Winchester lost his soul and morality, he didn't fall back into the habit of using demon abilities. Clearly, something or someone must act as a trigger to bring back Sam's powers, and God has both the ability and opportunity to do so. Chuck's desire to give the Winchesters a dark ending to their story provides the final piece of the puzzle - a motivation.
Arguably the biggest question surrounding the Equalizer wounds is whether either God or Sam will be killed as a result. Certainly, God doesn't seem too worried by his injury, and is more annoyed by not being at full power. Similarly, Supernatural is unlikely to end with just one Winchester brother dying, since viewers know that Dean will go to any lengths to resurrect his brother, and therefore the story would remain inconclusive. The bullet wounds may be unlikely to spell the end of God or Sam, but they could result in a fate far worse for the Winchester brothers - Sam and Dean being forced to throw down in a fight to the death.
Supernatural season 15 continues with Proverbs 17:3 November 14th on The CW.