Calthazar

Calthazar is the slash ship between Castiel and Balthazar from the Supernatural fandom.

The Third Man
Cas heads upstairs, where he finds Balthazar. Balthazar says that it's good to see him. Cas tells him that he grieved him, and Balthazar apologizes since he wanted it to seem real. Cas asks what he's doing, and Balthazar says he's doing whatever he wants. Cas asks if he stole the staff, and Balthazar says he stole a lot of things. Cas says that he knows Balthazar, and needs his help. Balthazar already knows, since he's been hearing all about Cas, and nothing's changed between them so he does want to help. Cas thanks him, and says he needs the weapons. Balthazar says not that, but Cas asks why he took them and ran away. Balthazar says it's because he could, and is following in Cas' footsteps from when he stopped the big plan and gave the angels freedom. Cas says that this is what he does with it, and Balthazar says that Cas gave him the ability to do anything so he's trying everything. Cas says that he needs to beat Raphael, and asks for the weapons again. Balthazar laughs and says that the fighting will never stop, no matter how much Cas believes he can. Better to grab something valuable and fake his own death. Cas says that he's insane, and that Raphael knows he's alive by now. He says that Raphael can try. He also says that even with everything going on, he still happy to see Cas, even with the stick up his ass. Thunder crashes, and Balthazar asks if that was Cas. Cas shakes his head no, and Balthazar takes that as his cue to go. He tells Cas to tells Raphael to bite him, and disappears.

Just as Raphael is about to stab Cas, Balthazar appears behind him and turns his vessel to salt. Cas gets up, surprised that he came back. Balthazar says that Raphael will have to look for a new vessel, giving Cas a head start on him. Balthazar says till next time, confusing Cas, when Dean lights a ring of Holy Fire around him. Dean won't release him till he takes the mark off Aaron's soul. Balthazar tries to reason with Cas, but he says that Dean has the floor. Balthazar then releases the soul, and demands to be released. Dean's against it, but Cas releases him. Cas says that his debt to Balthazar is now clear, and Balthazar calls it fair and disappears.

The French Mistake
Balthazar appears after Sam and Dean return to their earth and tells Raphael that he used them as decoys. Raphael makes his way to Balthazar, but Cas appears and tells him to step away, since he has the weapons. Cas is able to scare Raphael off. Balthazar tells Cas to not die by the sword he just got, and smiles at him before disappearing.

Let It Bleed
Balthazar calls Castiel to meet with him in the woods in the middle of knowhere. Balthazar says it's so good of him to come. Castiel is confused as to why Balthazar summoned him. Balthazar asks if he can ask Cas a direct question. Cas says of course, and Balthazar asks if he is in flagrante with the king of hades. Castiel answers, of course not. Balthazar chuckles and says "Always were such a terrible liar. So it's true. Alright then, why?". Cas replies that it is a means to an end and Balthazar should understand that. Balthazar says, "Oh absolutely. But what is the end here exactly? Raid Purgatory, snatch up all the souls.." Castiel interupts saying, "To win the war." Balthazar assumes that Castiel will be the vessel for the souls from Purgatory and Cas says that it seems like the only way. Balthazar counters that it could be too much juice for Cas and then Cas will explode and take a big piece of the planet with him. Castiel insists that that will not happen. Balthazar says sure, but to tell him that this plan is entirely risk free. Cas says he's sorry that he didn't tell Balthazar but he needs to know if Balthazar is with him or not. Balthazar smurks, chuckles and then sighs, he says "Fine, in for a penny, in for a pound." Castiel questions how Balthazar knew about the deal with Crowley, and Balthazar says Sam and Dean since they are all worked up about the kidnapping thing.

Later Balthazar returns to Bobby's house where Sam and Dean are and says that they need to talk. Sam asks why. Balthazar says that he is offically on their team (Sam & Dean's team). Dean doesn't believe him and Balthazar says it's for servival, because he asked Cas some questions and he didn't like Cas's answers. Balthazar is worried that Cas is too confident about taking the souls from Purgatory as he said that Cas would be absorbing a million nuclear reactors. Balthazar say that he will be their double agent and that he found where Crowley was keeping Ben and Lisa but he couldn't do anything because it was warded against angels, probably because Crowley doesn't trust Cas and makes a comment about how that marriage (Crowley and Cas) is going swimmingly.

The Third Man

 * Cas tells Sam and Dean they need to find Balthazar before Raphael.
 * Cas tracks down Balthazar.
 * Cas tells Balthazar that even he knows a literal frog in the throat is a bad joke.

Appointment In Samarra

 * Balthazar asks why they haven't Cas instead of him.

The French Mistake

 * Balthazar calls Cas, Cassie.
 * Balthazar explains to Sam and Dean what happened to Cas.
 * Cas tells Sam and Dean that it was Balthazar's idea to use them as bait.

My Heart Will Go On

 * Balthazar tells Sam and Dean to summon Cas instead of him.

Let it Bleed

 * Balthazar says that he already knew that Crowley was alive because Cas told him.
 * Sam and Dean tells Balthazar that Castiel has made a deal with Crowley.
 * Balthazar lies to Sam and Dean about knowing Cas' deal with Crowley.

Fanon
On AO3, Calthazar is the most written ship for Balthazar and the sixth most written for Castiel.

Fandom
FAN FICTION

TUMBLR

WIKIS
 * Castiel/Balthazar on Super-Wiki

Trivia

 * In addition to Castiel's common nickname of "Cas", Balthazar also calls him Cassie.