According to the YT documentary I watched they were into S&M (no prizes for guessing which of them was the dom and which the sub). It's suggested that Brando liked to psychologically torture Dean, who followed him around like a love-sick puppy.

I choose to believe the gossip because finally! ... an RP pairing that I can feel reasonably comfortable discussing on a public forum. I've long since accepted that RPF is a valid thing and have climbed down off my high horse but it's still a bit weird to me personally (maybe it's a Gen X thing). I was wrong to judge others though; I see that now and I'm sorry I did so.

Anyhoo, back to James and Marlon. If the rumour machine is that strong (I could find no contradictions) I'm more than happy to jump aboard the Deando train (or maybe Marlames?).

Oh, and a special shout-out to Cary Grant and Randolph Scott (I've known about their devotion to each other for ages); fellow actors called them Hollywood's happiest couple. I didn't even have to put their photos side by side; this is a genuine portrait of the two of them from when they shared a home for over a decade: