I originally wrote about this elsewhere but I felt like sharing it too because I think I put words on why Ja'far's loyalty feels so soul-crushing and wrenching and agonizing and everything to me.
I think Ja'far's devotion to Sinbad hurts so much because it's not a blind loyalty. He doesn't agree with everything Sinbad does, he will even confront him if needed. Sinbad said it himself; Ja'far is the only one that sees the bad things about him and will say it to his face (I'll come back to that later). Ja'far isn't those kind of loyalty that are like "My king does that so he must be right", on the contrary he's veryyyyyyyy well-aware of Sinbad's rights and wrongs, of where he comes from and what he has gone through. He knows his limits, he knows his flaws, as much as he knows his qualities.
Ja'far's loyalty is not about blindly agreeing, it's about never leaving.
Even if he's fully against Sinbad's doings, even if it hurts him to the core, gosh he could hate Sinbad with all his soul that he'll never leave. No matter what happens, Ja'far never leaves, and never will. Despite everything, despite the aching pains, despite the betrayals, Ja'far stays.
I think there is no more deep, devoted, and unwavering loyalty than that.
AND THAT'S WHY THIS. THIS SCENE. THIS SPECIFIC SCENE HAUNTS MY DAYS.
Like I said, Ja'far's loyalty is about confronting Sinbad when necessary, but staying nonetheless. It's a quality that SINBAD HIMSELF acknowledged and thanked Ja'far for. Sinbad needs to be confronted and opposed to stay on the right track, he himself is aware of it.
And here, Ja'far realizes that this no longer stands.
Yes it was not aimed at him, but gosh look at his face. You can't tell me he didn't take it for himself as well. He's realizing that Sinbad will no longer allow anyone to go against him, no matter how close they are to him. The very core of their relationship is gone. The role Ja'far was supposed to fulfill is no more.
The last thing he can do, is stay.
Because he's like that, even if Sinbad doesn't need him anymore, he'll stay.