Franco-Sicilian Defense Theory I am wondering what the main lines and point of the Franco-Sicilian Defense are for Black. I could barely find any theory about it online, and it' is my favorite opening as Black. As such, I am looking to improve on it. Any reference material will also do!
I also wonder why it is so rarely played. The engine doesn't hate it that much, and it fights the center very well, as well as allowing for a quick queen and dark-squared bishop battery in the midgame. So what is the effective response from White that makes it so unplayable? I have yet to encounter one.
[FEN &quot;&quot;]

1. e4 e6 2. d4 c5
It is certainly playable. The main drawback is that you give White the choice between two very different mainline openings:

3.Nf3 transposes to a Sicilian, where Black is already committed to e6 (Kan, Taimanov or Scheveningen, but no Najdorf, Sveshnikov, etc.).
3.d5 reaches a Benoni structure and may transpose to a mainline Benoni if White later plays c4. But in some lines White may profit from not having played c4, e.g. by posting a strong knight on c4 instead.

So you are giving White a pleasant choice, and you don't really gain anything in return. If you are prepared to play the Sicilian, then why not meet 1.e4 with c5 straight away? Sure, White could choose some Anti-Sicilian line, but most true Sicilian players feel that these are not as challenging as the Open Sicilian, so they have no need of a move order that tries to trick White into playing the Open Sicilian.
Additionally, the Benoni is of course far less popular than the Sicilian, which is another reason for your move order being played so rarely.