When Halsey is being interviewed throughout Halo 4. She even says “you want to replace him” to the ‘Mysterious’ man we never see. This bring us to the emblem on the new Characters chest. ONI - Office Of Naval Intelligence. Taken from the Halo Wiki - “Although it is under the jurisdiction of the UNSC Navy, ONI appears to report directly to HIGHCOM (UNSC High Command)” there’s lots about ONI and their “shadowy” “top secret” activities on there too.This further backs my theory. The UNSC High Command want Chief gone. They’ve finally created a new Spartan that matches up to Chief and ONI have been assigned the task of hunting him down. This explains the first trailer we saw of the game back at E3 2013. Chief is looking for Cortana whilst being hunted down by a new Spartan. His replacement. Let’s also bare in mind that ONI and High Command want to cover up the abduction and abuse of children for the Spartan II cause. Chief is a Spartan II. I might be wrong. But this adds up to a T. Even though this is to early to tell, now knowing that Agent Locke isn’t good (I assume) this all adds up. I just hope they dont kill chief off because with all the crap he has been through it shouldn’t be that easy for Locke to take him out.
Now looking at the new Agent Locke ad - YouTube , I believe this is 95% accurate and I had this theory from way back in E3 2014!!!
Also I think Locke is suppose to resemble Arbiter in the way of how Arbiter was lied to, deceived, and betrayed by his commander. I bet ONI lied to Locke and Arbiter telling them Chief betrayed everyone, in order to get what they want, to get what they thought was right. ONI is the new Covenant, I’m calling it now!