1G Brake flare nut stuck

[Red Rider]

While replacing a brake hose, I was able to unthread the flare nut, but the nut stayed glued to the brake line. I was able to pull the clip and unwind it by turning the entire hose. How do I free the flare nut from the brake line? I tried gripping the brake line with pliers as tight as I dared, and no joy.

Who has some magic for me?

 

[NOSLO2PT0]

Penetrating oil and slowly work it back and forth. Or try a little heat with a propane torch while slowly applying pressure back and forth