It can't be a new Monitor.

[Frogwart]

Bear with me here...
From Merriam Webster Online:

GUILTY
Function: adjective
1: justly chargeable with or responsible for a usually grave breach of conduct or a crime 2 obsolete : justly liable to or deserving of a penalty 3a : suggesting or involving guilt <guilty looks> b : aware of or suffering from guilt <guilty consciences>
SPARK
Function: noun
The most interesting, apt definition: 4 : something that sets off a sudden force <provided the spark that helped the team to rally>

PENITENT
Function: adjective
: feeling or expressing humble or regretful pain or sorrow for sins or offenses
TANGENT
Function: noun
Again, the most pertinent: 3 : an abrupt change of course : DIGRESSION <the speaker went off on a tangent>

ADJUTANT
Function: noun
1 : a staff officer in the army, air force, or marine corps who assists the commanding officer and is responsible especially for correspondence
2 : one who helps
REFLEX
And a different definition than what one initially thinks when hearing the word reflex:
a linguistic element (as a word or sound) or system (as writing) that is derived from a prior and especially an older element or system.

I agree with Kiloh's statements about GS and PT. Their names and actions as we've seen them show their culpability in the Halo events to date. I don't think AR has anything to do with the human body-related definition of the word.

AR may be a Forerunner construct specifically designed for communication and assistance, or "help" from "an older element or system"--perhaps that system we see being built by the "new gods" mentioned at http://www.halo3.com/comic/