Before I start, I know this theory holds absolutely no water in book cannon. I am taking into account Ryan Condal's demolishing of George's Source material as the foundation of this theory.
I've had this thought on my mind since the last season of HOTD. It's obvious to anyone who's read the books and any George R.R. Martin fan that the show has gone completely off script from how George himself envisioned the story of HOTD.
With the exclusion of Maelor, Luke's death being an accident (which was actually a decent change in my opinion), The Dragon pit/beast beneath the boards debacle, Laenor's escape, the list goes on.
I believe the Ryan Condal is setting up Criston Cole as the Shepherd. The Shepherd in the books is the character who leads the march on the Dragon Pitt, whilst Rhaenyra holds Kings landing. If I had to bet, we'll be seeing this in the season finale unless Condal and HBO are still trying to milk the story for more seasons.
The Shepherd is described as a brother of the Faith of the Seven, one-handed, insane, and to look like a corpse (according to our very reliable mushroom, who's account of the dance seems to be pretty accurate according to the show). As for our other sources, Grand Maester Munkun theorizes the Shepherd was once a poor fellow, and Arch Maester Gyldayn believes the Shepherd must've lost a hand due to thievery. Even with these in universe details we don't know much about the Shepherd beyond his hate for all things Rhaenyra, Dragon, and Valyrian related.
Now I think that Criston Cole might end up serving the role of this Shepherd character for a few reasons.
- Criston Cole, while seemingly loyal to team green, has started to garner a strong anti-dragon sentiment within him. Starting with the battle of Rook's Rest in the show, its clear to see that Criston has realized the horror that dragon's have on a battlefield and the true carnage they can cause even while battling above a field. (Thinking of he dragon blood burning Hightower troops alive.)
- Criston already hates Rhaenyra and team black. The Shepherd hates Dragons sure, but he only really seems to hate speech against Rhaenyra in Fire and blood. He does hate all things Valyrian and seems to think that they are the doom of Westeros, however this is something that a battle-scarred Criston Cole may think as well. Cole has seen Aemond turn evil and ruthless, has been spurned by Rhaenyra, and fights under the shadow of dragons the whole war. It's not entirely out of the realm of possibility that he ends up hating all things Targaryen after this.
- (Big Spoiler warning here) >!Criston dies before the riots of kings landing when we see the Shepherd appear. !<When you take this into account, and combine it with Condal's clear "fuck the Source material and fuck George" mentality, I can see Condal turning Cole into this disgruntled crazed Targaryen hater who wants to see the death of all dragons. Following the Butcher's ball, a barely alive and maimed (handless) Cole could return to King's landing and lead the march on the Dragon pit. This also fits with Cole's heritage, with Cole being from a lowborn background the Shepherd's hate for the nobles and higher society of Westeros could fit, because Cole himself has essentially been a play thing for the Targaryen dynasty.
Now this theory has a few problems with it as well, with the obvious being that the Shepherd and his followers interact with King Aegon II and a few other notable characters from the show who should know Cole. However, I think that it's not entirely out of the realm of possibility and that Condal has made major changes already that have made this story not make much sense.
I mean the exclusion of Maelor, and the loss of King Aegon II 'the Dragoncock' Targaryen's Dragoncock means that Aegon and team Green, are fighting to ultimately put Jaehaera on the throne following Aegon. Which is literally the reason why the dance starts, with the whole "women can't rule" sentiment.
Thought this was just a fun theory that could happen, and if it did, I'd be extremely pissed and would hope they just reboot this shit in 10 years like they will with Game of thrones and get it right.