There is a specific reason why Crowley had red eyes in Supernatural, and it has nothing to do with late-night parties in hell. Played by Mark Sheppard, Crowley unsuccessfully debuted in the fifth season of Supernatural. Starting out as a humble demon at a crossroads — kind people summon him when they want to master guitar playing or resurrect a dead brother — Crowley gradually softens his evil edge as he spends time. Stalking/flirting with Sam and Dean Winchester. Crowley would eventually join the brothers and Castiel as a main cast member before heroically sacrificing himself against Lucifer in season 12 of Supernatural.
To the great displeasure of Sam and Dean, the demons of the “Supernatural” can perfectly merge with human society, inhabiting living bodies. Whenever the infernal people want to show themselves, their eyes will flicker from the ordinary gaze of a human host to an opaque, smoky black. The color of the demon’s eyes indicates his status and position in the hierarchy of Hell. Black—eyed demons are a standard type of Supernatural. The oldest and most powerful demons, such as Lilith and Alastair, have white eyes, and all the Princes of Hell have the infamous yellow hue that John Winchester saw the night his wife died.
Related: The only supernatural episode in which Dean Winchester is Not (and Why)
In Supernatural, Crowley’s eyes are red because it’s a special eye color common to crossroads demons. They may not be as old as the white-eyed demons and not as powerful as the yellow-eyed ones, but the crossroads demons still have greater privileges, greater abilities, and a higher status than the run-of-the-mill “Supernatural” demons. As a result, they are given their own eye color, which distinguishes them from the pack. In Supernatural, many other red-eyed crossroads demons were shown, including Guy, Jael, and, E… Snooki? These deal makers are able to collect souls in exchange for diabolical privileges, which gives them more influence than their black-eyed counterparts. Crossroads demons like Crowley also summon their hellhounds when a customer fails to make a payment due. Visually, the “Supernatural” uses red eyes to distinguish these crossroads demons from the rest.
Why Crowley’s smoke is also red in “Supernatural”
Crowley’s red eyes in Supernatural is easily explained by his status as a crossroads demon… but what about its red smoke shape? Wandering the Earth, Supernatural demons take the form of smoke. Then this smoke enters the human carrier (usually directly through the mouth) in the form of a “meat suit” in which you can walk. Unlike demon eyes, their smoke shape is almost always black — and this seems to apply regardless of rank, even the strongest Hellspawn adheres to the standard color. The only obvious exception is Crowley, who boasts a crimson-red smoke that matches his dreamy eyes.
“Supernatural” didn’t really explain why Crowley is the only red smoke demon in the series. His work at the crossroads is not to blame, as other supernatural villains of this rank appeared with red eyes, but black smoke, proving that these two traits are not inherently related. The most logical explanation is probably Crowley’s rather unique career rise in Supernatural. He starts out as the demon of the crossroads (the king of the crossroads, no less), but soon becomes the king of hell. No other rulers of hell have been treated with red smoke, but perhaps Mark Sheppard’s Crowley, who passed from the King of Crossroads to the King of Hell, somehow painted his gaseous form in a new color. On the other hand, the “Supernatural” hinted that powerful demons can control the appearance of their smoke, and Azazel takes the form of a skull. As trivial as it may sound, a deliberate shake-up of his smoky wardrobe would be very “branded” for Crowley from Supernatural.
