Against 1.e4 I go 1...g6, the "modern".
As for my "pet" line, in the sense that it is a bad opening that I love and with which I have decent results, it is still as black: 1.d4 c5 2.d5 f5?!
I don't use it too often though, because getting into an inferior position is not really my aim as black.
Do you have a "pet"? By "pet", I mean a pet chess opening. Yes, that opening you have study hours on and lost sleep over. That opening that you play with good results, no matter how many times people tell you it is "theoretically unsound". That opening which just like you spose (hopefully) you will never part with until death. I would love to know your pet line. If you have one, post it so I can see it. "Pets" are my favorite
So, do you have "pet"?