Bette Davis and Humphrey Bogart appeared in 6 films together, especially fine work together in "Marked Woman" and "The Petrified Forest".
What was their relationship like to each other during the filming of "Dark Victory"?
Not sure about any friendship they ever had, but they certainly (along with Cagney and other popular stars of the time), encountered similar problems with Warner Brothers.
In those days, a contract player wouldn't have the luxury of choosing what movies they did. If they wanted you to appear swinging from a chandelier in your underwear, you had to do it, or risk being suspended (the suspension was added to your contract: if the movie they refused took 3 months to shoot, that 3 months was added to your contract). Both would regularly turn down movies offered to them, which increased their 'servitude' to Warners.
As Davis (and later Bogart) got more popular, they were allowed to choose material, or were given first choice of popular roles (Cagney was also in this group). But in the early days, they often had to do B-pictures (read: crap), and didn't have a choice in the matter.