In a short I'm writing, this guy's reflection talks to him -- like an alternative to using V.O.---but not only does his reflection talk, but he'll step out of the mirror/glass and stand next to the guy and talk. So, what do I use for cues? I used ERIC for the real guy and ERIC #2 for his "subconscious"/reflection. Is that okay? Will the reader understand that it's not some clone or twin, but his thoughts manifest into another Eric?

I don't know if this makes sense, but if anybody understands what I'm saying, what do you think?

Of course, there is no firm answer for this.  As long as your intent is clear to the reader, you can call him whatever you like best.

Personally, I like one of your own suggestions -- ERIC'S REFLECTION

Okay, thanks bert!

I had a guy talk to himself in a mirror in one script. The character was BRAD and he spoke to and carried on a conversation with BRAD IN MIRROR. Lord of the Rings accomplished the Gollum/Smeagol conversations by establishing that each was a personality in their own characters so the script actually shows Gollum and Smeagol having their own separate lines to differentiate the personalities.

ERIC IN MIRROR sounds okay... but can I switch to ERIC #2 when Eric's subconscious is standing right next to him? Or switch to some other name like ERIC'S SUBCONSCIOUS, for example?

As long as it's clear, use what works. Clarity is going to be the real key in something like this.

That's what I'm saying. But I don't know if it's clear to the reader -- I guess I'll just have to post it and see if anybody gets it.

Well, if you have a total of 2 Erics, whether the second one is in the mirror or standing next to him or whatever, it would be a good idea to give him a consistent name based on whatever he really is in the story. I had come up with an Edgar Allan Poe story once where I had POE, the main character and POUGH, the invisible friend who he carried on conversations with.

You could have ERIC and ERIK, if it comes down to it, but define that ERIC is your main character and ERIK is Eric's subconscious or invisible friend or whatever. If real ERIC ever addresses his invisible friend by a name, that would be a solid idea. If he calls his other self "Eric" then calling him ERIK or ERRICK or some other spelling would work. Whether he exists or not should be brought out in the story.

Okay... I'll think about that.