Deputy Secretary of Awesome wrote...
This is really interesting. I was always curious what the "flames" could be symbolising. A warning? An attempt to fight the indoctrination? A premonition of doom? The idea that it represents "Anderson" and that kind of fit with Anderson as the "renegade" representation, plus his associations with the explosive Destroy option is an intriguing concept.
The doppleganger Shep is also completely creepy. That look he/she gives just felt sooo off. Not to mention the Catalyst "dopplegangers" Shepard's voice (both male and female) in the final scene...
Flames can represent much in this case: To be consumed, (to be overtaken with indoctrination); to be purged, (to remove the taint of what's bothing Shepard); to destroy or forshadow destruction, etc.
As to the Catalyst/Child's voice, it could easily be construed as a sign that he is a partial manifestation of Shepard's mind, thus taking on an element of his voice. Aside from that, the act of indoctrination appears to be heavily based upon demonic possession: mimicry, subtle twisting influence, the dissecting of families/friends, the loss of control of one's being, the hallucinations, nightmares, delusions, the EMF/ISF/USF factors, etc. all are elements of extreme hauntings/possession.
In the case of the child burning in Shepard's presence, this could easily be seen as symbolic of a temptation and rejection: traditionally, a demon cannot dwell within a pure vessel but will continue to tempt the target until its will is weakened, then beginning its takeover- Shepard may still cast out the indoctrination attempt in the last dream, but it already has its foot in the door, making its next attempt more likely to succeed. Shepard's will is weakened and the Reapers now have his number, so to speak.