Character interludes

Character interludes are a storytelling aspect of the Halo 3 campaign, in which either Cortana or the Gravemind telepathically address the Master Chief and often muse introspectively. During these interludes, the player's movements will slow drastically, as will their ability to turn and face another direction. A screen effect will also alter the display of the game. Referred to as "Cortana channel" and "Cortana effect" by Bungie employees, the character interludes is an attempt at weaving story into gameplay sequences without affecting the pacing.

During a Cortana interlude, the screen turns blue, and Cortana's image flashes in and out of focus on the screen. Her voice contains a slight echo and sometimes a deeply-pitched distortion effect, and her image erratically "jumps" around the screen. During a Cortana interlude there will also be a noise sounding vaguely similar to the noise heard if one places a seashell in their ear.

During a Gravemind interlude, the player's view become murky green, and tentacle-like imagery can be seen at the edge of the screen. The screen will shake in unison with the Gravemind's voice, shaking far more violently if Gravemind is screaming or yelling in anger at John-117.

The Cortana interludes depict her descent into rampancy, while the Gravemind interludes are used to convey the point of view of the Flood. It is possible in co-op mode for one player to trigger the interlude while the other player is behind fighting enemies that the first one skipped. During any of these interludes, the player is completely immune to damage and will not be attacked even by nearby enemies.

The Halo Evolutions story Human Weakness revealed that the Gravemind had successfully hijacked Cortana's system, allowing him to speak with her voice. This was part of his plan to persuade Cortana and John-117 that Cortana was descending into rampancy. Cortana battled the Gravemind, trying to hold onto the data about the Portal and the Ark. She ends up creating multiple copies of herself to distract the Gravemind and twice they apparently chime in during her conversations with the Gravemind. One adds the "I am a monument to all your sins" part of one of the interludes while the rest is Cortana defying Gravemind to buy the Master Chief time. Cortana places the message onto Indulgence of Conviction by composing it with the help of a copy and then transmitting it to that ship through Gravemind's link to it, with part of it being coded to seek out and upload itself to the nearest data device. Gravemind then reveals that he knew and helped out as he wanted to lure John-117 to the Flood-infested High Charity, but did not know what the message actually said.

The ninth Halo Legendary Crate Data Drop discusses the "Cortana moments" further, revealing that John-117 did recieve the messages throughout the later weeks of 2552, believing them to be software glitches and anomalies. His MJOLNIR armor was later checked out by a trauma analysis team, with the Cortana transmissions officially ruled to be "residual interface anomalies"; echoes of Cortana's personality matrix left inside the armor systems after her departure. After reuniting with Cortana, John never discussed the transmissions, and later in 2553 his armor filed a Software Trauma Analysis detailing the supposed-glitches. Following Cortana's sacrifice during the New Phoenix Incident, John-117 was debriefed by the UNSC, with the Cortana transmissions a subject of this discussion, with analysts pointing out that Cortana's ability to communicate across thousands of light years may present a vital security flaw in UNSC systems - a shadow of events to come.

Arrival

 * Cortana (Voice Only): "They let me pick. Did I ever tell you that? Choose whichever Spartan I wanted. You know me. I did my research. Watched as you became the soldier we needed you to be. Like the others, you were strong and swift and brave. A natural leader. But you had something they didn't. Something no one saw...but me. Can you guess? Luck. Was I wrong?"
 * The speech references the conversation on Luck between Catherine Halsey and Cortana when they were selecting John-117 as the Spartan Cortana would like to be paired with.


 * Cortana interlude: "Don't make a girl a promise... if you know you can't keep it."
 * The line is a direct quote from Cortana when John-117 left High Charity in Halo 2 campaign level High Charity.

Sierra 117

 * (Cortana interlude): "Could you sacrifice me to complete your mission? Could you watch me die?"
 * The line references the question from Halsey to Cortana when they were selecting John-117 as the Spartan Cortana would like to be paired with.

Crow's Nest

 * (Cortana interlude): "You have been called upon to serve."
 * The line is a direct quote from Halsey when she first gathered and addressed the SPARTAN-II candidates.
 * (Cortana interlude): "You will be the protector of Earth and all her colonies."
 * The line is a direct quote from Halsey when she first gathered and addressed the SPARTAN-II candidates.
 * (Cortana interlude): "There will be a great deal of hardship on the road ahead."
 * The line is a direct quote from Halsey when she first gathered and addressed the SPARTAN-II candidates.
 * (Cortana interlude): "You will become the best we can make you."
 * The line is a direct quote from Halsey when she first gathered and addressed the SPARTAN-II candidates.
 * (Cortana interlude): "This place will become your home."
 * The line is a direct quote from Halsey when she first gathered and addressed the SPARTAN-II candidates.
 * (Cortana interlude {Voice Only}): "This place will become your tomb."

The Storm

 * (Cortana interlude): "I have defied gods and demons..."
 * The line was also featured in the Halo 3 announcement trailer.
 * (Cortana interlude): "I am your shield... I am your sword."
 * The line was also featured in the Halo 3 announcement trailer.
 * Cortana {Voice Only}: "This is the way the world ends..."
 * The line is was also featured in the Halo 3 announcement trailer. Both were alluding to the first Cortana Letter and the poem The Hollow Men by T. S. Eliot.

Floodgate

 * (Cortana interlude): "Chief. {background mumbling} I can't tell you everything...it's not safe. The Gravemind... it knows I'm in the system..." {background mumbling}
 * This is later revealed to be part of Cortana's message to the Master Chief recovered from Indulgence of Conviction.
 * (Gravemind interlude): "Do not be afraid. I am peace... I am salvation."
 * (Gravemind interlude): "I am a timeless chorus. Join your voice with mine, and sing victory everlasting!"
 * The line was also said by Gravemind to Cortana in an attempt to convert her after she had left the message on Indulgence of Conviction.

The Covenant

 * (Cortana interlude): "It asked, and I answered. (Her tone turns bitter) For a moment of safety, I loosed damnation on the stars."
 * (Cortana interlude): "I'm a thief... but I keep what I steal."
 * The line foreshadows the reveal of Installation 08 and when Cortana "stole" the activation index of Installation 04 in Halo: Combat Evolved campaign level Two Betrayals.

Cortana

 * (Gravemind interlude): "Child of my enemy, why have you come? I offer no forgiveness... for a father's sins passed to his son."
 * (Cortana interlude): (A strange mix of cries of agony and manic laughter.)
 * (Gravemind interlude): "Of course, you came for her... We exist together now. Two corpses in one grave."
 * Apart from the first line, the line is a direct quote from the Gravemind Halo 2 level High Charity.
 * (Cortana interlude {Voice Only}): "A collection of lies; that's all I am! Stolen thoughts and memories!"
 * Although Cortana wanted to snip back at Gravemind for his "two corpses in one grave" remark, Gravemind had hijacked her voice output, changing what she wanted to say.
 * (Gravemind interlude): "And yet, perhaps a part of her remains?"
 * (Cortana interlude {Voice Only}): (Laughter, in response to the Gravemind.)
 * (Gravemind interlude): (angry) "Time has taught me patience! But basking in new freedom, I will know all that I possess!"
 * (Cortana interlude {Voice Only}): "May I speak with you, please?... What's your name? It's very nice to meet you! ...You like games? So do I."
 * The speech references the conversation on between Dr Halsey and John when they first met.
 * (Cortana interlude): "It was the coin's fault! I wanted to make you strong; keep you safe. I'm sorry, I can't."
 * Only available upon accessing the eighth Terminal, the line is a reference to Dr. Halsey's examination of a six-year-old John before he was drafted into the Spartan II program. Halsey flipped a 21st century quarter, and John correctly identified the eagle side of the coin that was about to the hit the ground before it did. Halsey explained to then-lieutenant Jacob Keyes that this was a means of weeding out the "unlucky" applicants, as there were only a limited number of slots available.
 * (Cortana interlude {Voice Only}): I'm just my mother's shadow. Don't look at me, don't listen! I'm not what I used to be..."
 * (Cortana interlude): (panicking) "I have walked the edge of the abyss. I have seen your future. And I have learned!"
 * The lines are direct quotes from the first Cortana Letter.
 * (Gravemind interlude): (angry) "Submit! End her torment and my own!" 
 * (Cortana interlude): (panicking) "There will be no more sadness, no more anger, no more envy!"
 * The line referenced rampancy'' and quoted the first Cortana Letters.
 * (Gravemind interlude): (angry) "You will show me what she hides, or I shall feast upon your bones!"
 * (Cortana interlude): (speaking in a flat, monotone voice as though brainwashed. Her image is green). "This is UNSC AI Serial Number CTN0452-9. I am a monument to all your sins." ''
 * The first line was a desperate attempt from Cortana to speak to John-117, and the second line was the result of Gravemind hijacking her voice, with the message being a direct quote from Gravemind in Halo 2 campaign level Gravemind.
 * (Gravemind interlude): (roars) "At last, I see! Her secret is revealed!"

Halo

 * (Gravemind interlude {Voice Only}): (taunting, angry) "Did you think me defeated?!"


 * (Gravemind interlude {Voice Only}): (enraged) "I have beaten fleets of thousands! Consumed a galaxy of flesh and mind and bone!"


 * (Gravemind interlude): "Do I take life, or give it? Who is victim... and who is foe?"


 * (Gravemind interlude {Voice Only}): (sadly, defeated) "Resignation is my virtue... like water I ebb and flow. Defeat is simply an addition of time to a sentence I never deserved, but you imposed."

Fiction

 * After any Cortana/Gravemind interludes, there will be vertical lines running down Master Chief's HUD (or visor). The armor's helmet automatically refreshes the visor afterward.
 * In Sierra 117, the corpsman tells the player that during the first Cortana interlude, John-117's vital signs momentarily ping KIA, which may be the reason the player slows down, as the armor functions using the user's neural signs instead of muscles, which makes it still possible for the Master Chief to move even if his vital signs have stopped but his brain is intact and functioning.
 * Many of Cortana's lines, as noted above, are repeated lines Dr. Halsey has said before. One such line is, "You will be the protectors of Earth and all her colonies.", which Dr. Halsey says to the six-year-old Spartans in Halo: The Fall of Reach. Cortana also recites a few lines from the Cortana Letters and Halo 3 announcement trailer.
 * Dialog cut from the game featured many more references to both the novels and the Cortana Letters. For example, Cortana reciting the entire poem from the first Cortana Letter was recorded, although only parts of it are used in the final game. Cortana's cut dialog also included more references to Dr. Halsey's lines from the novels, such as the entirety of her speech to the Spartan inductees. The Gravemind also had more lines recorded, many of them being extended versions of its dialog featured in the final game.
 * In one of the last Cortana interludes, Cortana turns green. In Halo: Combat Evolved, upon entering the computer systems of Installation 04's Control Room and being exposed to the wealth of information contained there, Cortana also turns green and begins to behave quite oddly, experiencing sharp mood swings and displaying rude contempt for both the Master Chief and 343 Guilty Spark. It is noted in Halo: First Strike that exposure to such floods of raw information can greatly shorten the operational lifespan of a smart AI. The presence of green, therefore, may serve as an indication of rampancy (a reference to the AI Durandal in the Marathon series).

Gameplay

 * If you use the 3 Player Local Co Op glitch, during the Cortana interludes, the game will freeze because it was not meant for three-player split-screen campaign. Strangely, Gravemind interludes function normally.
 * If you take a screenshot of a interlude from the Theater, it will appear completely black in the screenshot gallery, adding some mystery to the entire perception. In the level The Covenant, if one forces a M12 Warthog into the Citadel (using the Wraith) and drives straight for the door, nonstop, they may activate both the Cortana interlude and the preceding cutscene at the same time. During this, the cutscene will have a bluish tint with two extra blue layers. This effect could be what causes screenshots during Cortana interludes to blank out, although it could also have been a desired side effect of Bungie to prevent all but cutscene screenshots of Cortana from being taken.
 * If there is background music playing during the gameplay, it will pause during any Cortana/Gravemind interludes.
 * If a interlude occurs while one is driving a vehicle, it slows down as well. However, if the player is a passenger, then the vehicle goes at normal speed.
 * Interludes will not slow down a jump, a melee, or attacking with something such as the Type-2 gravity hammer.

Miscellaneous

 * Excluding Arrival (where it should still be noted there is a Cortana interlude before choosing your controls) there are seven levels where the Gravemind and Cortana interludes occur. Excluding the interlude in Arrival, there are twenty-eight interludes in total—seven times four.
 * During the level The Covenant, as the player enters the Citadel during the Cortana interlude, if they look at the screens that, during the next cutscene, show the Prophet of Truth, Cortana also shows up on them.