If you were confused about Batman Arkham City’s ending with the Real and Fake Jokers, or did not understand what Protocol 10 meant, then this is the guide for you!

WARNING: This article contains MAJOR SPOILERS. If is HIGHLY RECOMMENDED you read this only AFTER beating the main campaign of the game.

Let’s first start with explaining Protocol Ten.

From the beginning of the game, you hear Hugo talk about this “Protocol 10” he is about to commence. But what is  this Protocol?

When you encounter Joker at the Steel Mill for the first time, and he infects Batman with the diseased blood and tells him he had sent infected blood to hospitals all around Gotham, Batman thinks that Protocol Ten is a plan to kill all of Gotham’s citizens by spreading the infected blood. Not very creative. But when Batman confronts Joker with this, Joker has no idea what’s Protocol 10. He has never heard of it. So it must be something else.

As you progress into the game, slowly you learn more and more clues about Protocol 10. Here is what it REALLY means:

Protocol 10 was a plan devised by Hugo Strange. The plan involved the following:
1)    Tell Quincy Sharp, who was the Warden of Arkham Asylum,  to “ignore” the cruel experiments that Hugo was conducting on the inmates of Arkham Asylum. In return, Hugo Strange would help Quicy become Mayor of Gotham City
2)    Once Quincy Sharp becomes Mayor, Hugo blackmails him into forming Arkham City and put Hugo Strange in charge, otherwise he will reveal the truth about how he got to be elected mayor.
3)    All prisoners were to be gathered in Arkham City
4)    Hugo Strange’s private mercenary army, called “TYGER” would be in charge of enforcing order inside Arkham City
5)    Strange would also arrest political prisoners who knew too much about his plan (such as  the Mayor himself) and anyone who would try to shut down Arkham City (Such as Bruce Wayne)
6)    Now, Strange incites violence between the all the criminal factions in Arkham City (Joker, Two Face, Penguin) by stirring up all sorts of trouble between them
7)    Strange will sell High tech weaponry to ALL of the sides, so that they can fight amongst each other with greater firepower
8)    Obviously, violence erupts between all the factions in Arkham City due to Strange’s manipulations
9)    Strange now goes to the city council and seeks approval in using TYGER to eliminate all the criminals, since the violence is out of control
10)     The city approves, and Arkham City is destroyed, including killing everyone inside
11)    Hugo Strange is then seen as the savior of people, having eliminated the “bad seeds” in society. His TYGER army gains lots of influence and budget.
12)     He goes to other cities, such as Metropolis, and offers to do the same for them.

Behind all of this though, Ra’s Al Ghul was pulling the strings. He had offered Strange to replaces him in the League of Assassins as well as the gift of immortality had he succeeded with the plan. But Batman managed to stop him.

Ok, I hope all of this is clear. If you have questions, feel free to leave a comment.

Ok, now lets see what happened with Joker. I mean there was a real Joker, fake Joker, sometimes it was hard to tell who is who. And how come the Joker did not have the cure in the end if Harley Quinn had stolen it from Batman?

So yes indeed, there were two Jokers – The “Real” Joker, and the “Fake” Joker. Fake Joker was actually Clayface. Real Joker was the one who was sick.

When Batman enters the Steel Mill for the first time, he sees a dead Joker on the Wheelchair. That was the REAL Joker who somehow managed to fake his vital signs and fool Batman into thinking he was dead. Then the FAKE Joker (Clayface) attacked him from behind and gags him unconscious.

When Batman wakes up, he is talking to the REAL Joker, who is sick with the virus.

Confused already?

Later Batman has Mister Freeze create the cure, and when Freeze refuses to hand over the cure to Batman, Batman and Mister Freeze have a big battle. During that battle, Harley Quinn steals the cure from the safe. Furthermore, while Batman is chasing Harley, the Joker distracts him by shooting down Vicki Vale, making Batman stop chasing Harley as he goes to rescue the reporter. So Batman believes Harley had lots of time to make it to the Joker, who  now has the cure.

Unknown to Batman, Talia intercepts Harley in the Steel Mill and steals back the cure. Batman later finds Harley tied up in the Steel Mill but he does not realize she never made it to Joker, since everyone is talking about how Joker looks good now and is no longer sick.

So how come, when Batman enters the Steel Mill everyone says the Joker looks well and has been cured? Joker knows morale is not good amongst his gang seeing that their leader is sick and could die. So he uses Clayface again to be him, and make people thing that he got well and is no longer sick. Everyone, including Batman, thinks Joker drank from the cure, but that is not the case as the cure never made it to him.

When Batman confronts him, he sees a healthy joker, which is the FAKE joker. When he gets trapped under the Debris, Talia shows up and offers Joker the gift of immortality in exchange for sparing Batman which Joker accepts since that would save him from the disease.

When Batman enters the Movie Theater, The FAKE Joker is holding Talia. Joker asks Batman for the cure, and Batman does not understand why because he thought Joker already had the cure. Then suddenly Talia stabs the Fake Joker and looks like she killed him. Batman starts to piece the clues together in his mind, and suddenly realizes what is going on, but before he can warn Talia that the real joker is still alive and is probably inside the theater, the real Joker shoots Talia, at which point she drops the cure from her hand.

Batman now fights Clayface (The Fake Joker) who didn’t really die and has grabbed the cure. He defeats him and takes the cure from him and drinks it, becoming healthy again. The Real Joker stabs Batman in the arm, causing him to drop and break the vial, so the real Joker dies since there is no more cure. Batman tells him before his death, that even with everything that Joker has done to him, Batman would still have let him drink from the cure if he had asked. Joker finds that funny.

One last issue I would like to clarify:
After rescuing Vicki Vale, Batman receives a message from Alfred that they have found a cure to the virus, and are sending him a dosage. Batman arrives to the drop off location and injects the cure, but then falls unconscious and wakes up in front of the Mad Hatter. This “Cure” that Batman took was not a real cure. It was just an hallucination, a trick by Mad Hatter to lure Batman into an ambush. Which is why even after supposedly injecting himself with the “Cure” from Alfred, Batman is still sick.