Unfortunately, I was too swamped and too distracted to properly prepare for Juliet Hellhound Week. So I only have some half-formed ideas and doodles to share for @juliet-hellhound-week.
My current Juliet HC is centered around the idea of transformation. That Juliet isn't always a hellhound.
In one version of the HC, she transforms into human form when she wants to more directly engage with demons and humans and angels to accomplish an important mission.
She could transform into more than one form, I think; but currently I am thinking of this form of "human" Juliet:
She is very tall, and very large, with very dark skin (a bluish black), long thick braid that hangs to her tailbone, has patterns (like a kind of mobile tattoo) that flash on her skin because she is basically a living spell. Her weapon is a curved blade (like a claw) that she could summon at will.
Here is a crudely drawn doodle, the reference photo being the album cover from the song called Bicho Solto that inspired this HC.
"I domesticated myself
To stay in the game
But make no mistake, fool,
I' m still a feral beast"
A little more detail below the cut. I will post version 2 tomorrow (very short).
Version 1: Hopeful Monsters
Basically after S12 finale and Crowley's death, things happen just as in the show: Asmodeus claimed the throne of Hell and Jack fell in with the Winchesters.
In Hell, it turned out that the demons Asmodeus put into positions of power got assassinated one after another, and there were signs they had been interrogated before the killing. Hell became a powder keg of paranoia, fear, and discontent. This was Juliet's doing as she took on human form so she could investigate the truth of Crowley's death, for vengeance but also to uncover clues to resurrect Crowley.
At the mean time, Jack was made to believe he was an evil monster or that he needed to be reformed by benevolent humans. After one of Dean's angry outbursts, he blipped away to hide in fear and anxiety (as in s13e2). Asmodeus and his minions immediately located him. Afraid of himself, confused about who he was, Jack couldn't figure out how to use his power, and was captured and imprisoned in Hell.
He was freed from Hell's prison by a very tall, very large woman with a curved blade, who was of course Juliet in human form. In her investigations, she learned that the Nephilim had great power so she decided to recruit him on a mission to invade the Empty and get Crowley out.
Although grateful for her assistance, Jack told Juliet she shouldn't put her faith in him because he was a monster. Juliet congratulated him for his gift, and told him she herself was one of the greatest of monsters, and another great monster was just what she needed to dismantle a world that caused the death of Crowley (she reluctantly threw in Castiel too to entice Jack).
So they went on an adventure to uncover secrets about the Empty and to collect the magic and tools and allies they would need for the rescue mission. It would be a long and difficult journey, and the story doesn't have a definitive ending. It ends with the two hopeful monsters disappearing into the night, while Hell was buzzing with rumors of the impending return of Crowley. A revolt was under way.