My NRC reputation is Merciful Thug, and I remember I had exhaust all dialog option about Elijah when I talked to Veronica...

However when I talk to Elijah just now, there is no dialog option - "You're Veronica's mentor. The Elder who lost HELIOS One."

Is it because I did not completely talk to Veronica about Elijah, or is it because my NCR reputation is not vilified?

How can I decrease NCR fame? I am playing on PC.

Maybe


Yes


A detailed list of console commands
http://fallout.wikia.com/wiki/Fallout:_New_Vegas_console_commands

ok...I set my NCR reputation to be vilified...but that dialog option is not there... :sadvaultboy:

This goes in the DLC section,.