To my understanding, there was a notable amount of people who didn’t like having to switch between 'Chief’s perspective, and that of the Arbiter’s, throughout the Halo 2 Campaign. So, I started to think about how 343 could handle the two leads of Halo 5.
Chose Your Campaign
So, right off the bat, on the Campaign start up screen, one of the options presented to the player will be if you’d like to go through it by default - switching at predetermined times during the Campaign - or individually. Individually will ask the player whose journey they’d like to play through; Master Chief’s or Agent Locke’s. Whoever is chosen, you would run through that character’s Campaign without ever having to switch perspectives. You want 'Chief only, you can have that - and vice versa. This would appease those who just want to experience the Master Chief, at least on their first run through of the game. I’m not sure it would have been a huge deal in 2, if they could make that choice. Play the 'Chief now, play the Arbiter later.
So it would be: Default – Master Chief – Agent Locke.
Changing Whilst You Play
It doesn’t end there, though. I was also thinking about after you’ve started a character’s Campaign. Maybe you want to switch roles. Maybe the two have converged, and now your interested in character X’s adventures up to this point. In this situation the game will give you an option to do so without ever having to exit back to the main menu. Press start, and below Save and Quit will be: ‘Save and switch’.
Save and Switch
Unlike the option to save and quit, this one will save your progress and then transfer you over to the other character’s Campaign. If you have yet to start character X’s story, the game will start it up from the very beginning. However, If you have, it will give you the option to select your most recent progress, or missions that you have already completed.
Seamless Switching
Another idea would be that once you’ve completed a mission, there will be some kind of prompt that allows you to switch between the two - once the outro cutscene for your current mission has completed. Instead of loading into character A’s next level, it will load into character B’s. I would say that if you chose to switch using this method - which is more seamless - you will either start from the beginning if you have yet to start character B’s story, or you will resume from where you left off. You would chose this switching method when you want to move more smoothly between each character, so having a menu come up where you can also select completed levels breaks the flow.
Perhaps you’re given the option to enable or disable the bookend transition prompts. If you enable them, you will be given a window to transition over during the concluding cutscene of every level. If you disable, you will be prompted only at the moments 343 would have them switch by default. So, in Halo 2, if this feature was available, you would be given the choice to switch to Arbiter after every level, or only on Metropolis, Regret, and Gravemind - the levels where the developers have dictated the transition.
Issues
Whilst I love this idea, I do see a big issue with it. Because you have no knowledge of character B’s story, when playing as character A, you may learn something that could spoil character B’s journey for you. Maybe when the two finally meet, something dramatic happens, and now you know that event will take place when you finally decide to start Character B’s Campaign. One character’s story will lose some impact, because certain big moments in his journey will have already been revealed.
[EDIT] In terms of any issues with spoilers, it would just be a case of designing the Campaign in a way that all the big story beats in both stories happens when they’re apart. If they do communicate at one point, it would be brief, and provide no exposition as to what’s been happening with character B.
Unlocking the End Game - to combat the issues of spoiling each Campaign
I was thinking that maybe they’d introduce new Campaign levels once you’ve played both stories to completion. After that, a final set of - end game - levels will unlock, which will be when everything goes down. At this point, both characters will come together and prepare for the final confrontation. If you’re now playing alongside the other, it’s not a case of spoiling the other character’s story, it’s a case of whose eyes are you playing through.