What the Halo 5 Legendary Ending Means for the Future of Halo

The Legendary ending for Halo 5: Guardians brings the game series back to its origins and teases the future of the franchise.

Halo 5 Legendary Ending logo


In this latest installment of the Halo franchise, a lot of advancements were made in the gameplay, the story, and the lore behind the universe. Among the most shocking developments was the return of Cortana and her betrayal of humanity.

The ending provided some interesting information for those looking to the future of the franchise, especially the Legendary ending. We last see Cortana (via a Guardian) chasing the USS Infinity. They manage to make an emergency jump just in time to avoid capture, and it’s clear that Thomas Lasky, the captain of the Infinity (which, by the way, is the single most powerful piece of technology that humanity controls), is completely powerless against Cortana and the Guardians. The Spartans were all but powerless against Cortana as well, just barely managing to rescue Master Chief and his compatriots with the help of another AI.

The Halo 5 Legendary ending, however, reveals a bit more. In that ending, we see a Halo ring orbiting a planet. We hear Cortana humming a tune and the ring suddenly lights up. Some would say the ring is activated, but that implies that it is about to be used (to wipe out all nearby life). It doesn’t seem to be activated yet, but it is powered on, at least. Remember that the USS Infinity was commissioned to find the Halo rings for decommissioning. Perhaps this is a ring that was shut down, and Cortana is powering it back up? So what does this all mean for Cortana’s intentions and the future of the Halo franchise?

The “Halo” is Back in Halo

A scene from the Halo 5 Legendary Ending

Well first of all, this Legendary ending suggests that 343 Industries wants to go back to the roots of Halo, namely…the actual Halos. Halo 4 and Halo 5 both completely avoided the Halos. That story seemed to be over, but it was still the namesake of the franchise, so I should hope that 343 Industries has not lost site of their importance.

But thankfully, it appears that the Halos will once again play an important role. I would not be surprised if much of the Halo 6 campaign takes place on a Halo once again. The USS Infinity made an emergency jump at the end of Halo 5, kind of like the beginning of Halo: Combat Evolved. Perhaps this is an intentional parallel. Also, contact with the Halos could also mean we’ll see the Flood again, since remnants survived on the Halo rings.

What Is the Tune Cortana Hums?

Cortana in our Halo 5 Legendary Ending discussion.

Nothing is random in a teaser like this Halo 5 Legendary ending. The tune that Cortana hums almost certainly means something important. But what exactly is the tune she’s humming, and what does it mean? This is a matter of some debate among fans at the moment.

We know one thing for sure: the tune can be clearly heard playing at the opening cinematic for Halo 5: Guardians, played in this case by a piano. Check out a comparison in the video below. The cinematic takes place in Dr. Halsey’s lab, but in a flashback to Reach, before the Fall of Reach. If you’ve played Halo: Reach, you’ll probably know what I’m talking about. So we know Cortana has heard this tune before in the lab. So is she just humming a familiar tune? Well it probably has more meaning than that.

The tune can also be heard during the game as the tune of Oly Oly Oxen Free, a code that the Spartans originally used to give the “all clear.” So it would have significance to Cortana from that sense, given her history with Master Chief. However, this still doesn’t answer many questions about why she’s humming it in this particular moment. Does it imply that she’s about to “clear” the galaxy of any potential threats (aka intelligent life)?

The tune also resembles something 343 Guilty Spark used to hum in the original Halo game. 343 Guilty Spark was an AI that went a bit crazy, and wanted to destroy life in the galaxy to contain the Flood. And that brings me to one potential theory.

Is 343 Guilty Spark Involved?

Guilty S

343 Guilty Spark was originally a human named Chakas who lived during the time of the Forerunners, nearly 100,000 years ago, and whose brain was used to create the AI. We know that he and another human named Riser were pre-programmed with a special song that would activate a cryptum. Is it the same song? Well it is programmed into humanity’s very DNA, so it is quite possibly the same one. What does it mean? If it activates a cryptum, could it activate other Forerunner technology, like say, a Halo? Food for thought.

But back to 343 Guilty Spark. He was thought to be exterminated at the end of Halo 3, but if you read the book Halo: Primordium, you learn that the remaining pieces of his consciousness were activated by humans on a research ship. At some point he learns that the Librarian (an important Forerunner) is still alive somewhere. He then takes over the ship to search for her, and that’s the last we hear of 343 Guilty Spark for now.

So one theory is that 343 Guilty Spark has control over, or is, Cortana. I doubt Guilty Spark has any significant hold over Cortana, since she seems to have a deep love of Master Chief. In Halo 5, she clearly seems to be the same AI/person that accompanied Chief. It doesn’t seem like Guilty Spark’s usual MO. But perhaps they were humming the same tune for different reasons. Or maybe it isn’t the same tune and this has nothing to do with Guilty Spark at all. That said, I’m sure we haven’t seen the last of him.

What is Cortana Thinking?

what is cortana thinking in the Halo 5 Legendary Ending

Of course, the big question is what does Cortana want with a Halo ring? The purpose of the rings is to wipe out sentient life across the entire galaxy. So if she is activating it, she probably intends to use or threaten to use it.

As a bit of background information: Cortana is now connected to the Domain, a huge repository of Forerunner information that dates back even before the Forerunners. Think of it as a massive Internet with some self-awareness and mystical qualities. Cortana’s connection with the Domain is what led to her becoming the villain of the game. She saw the big picture and knew how to bring peace by basically becoming a tyrant and forcing everyone to obey her wishes.

Many assume that Cortana has lost her mind or that someone (like Guilty Spark or the Domain itself) is manipulating her. After all, she did go rampant at the end of Halo 4. Maybe she’s still a little insane. However, I doubt this is the case. I think she truly believes in what she is doing, and could, in fact, bring peace. However, she makes one mistake of valuing peace over freedom. So she would consider enslaving or perhaps even committing genocide to maintain that ideal peace.

So is Cortana prepared to wipe out life with the Halos? I think it’s very likely. When she traps Master Chief in a cryptum, she does mention that she might wake him in 10,000 years, suggesting that she plans to do what the Forerunners did, destroy all life and repopulate.

So to sum up, we…still don’t know very much. We know Cortana activated the ring, possibly through the use of a special tune meant for that purpose. At the very least the tune is symbolic of such. And we can assume that Cortana has hostile intentions with that ring. She either means to wipe out sentient life, or threaten such an act to keep the peace. She likely has good intentions but is blinded by the knowledge of (and potential bias from) the Domain. Also 343 Guilty Spark is likely involved, or soon will be. But at the very least, we will likely visit a Halo ring again in the Halo franchise.