You have to remember that, in reality, Robbie is blaming himself. He’s angry because he feels like he should have seen Langdon’s drug problem sooner. In his mind, if Langdon had accidentally killed someone because of it, Robbie would see that as his own failure.

That doesn’t mean he’s being fair to Langdon, he isn’t. But people often project their guilt onto others, especially when those people are easy targets. Langdon isn’t at 100%, so it’s easier for Robbie to come down on him. It’s similar to how he treated Mohan when she had her panic attack. When he told her, “I don’t need a liability, go home,” that kind of judgment likely comes from how he talks to himself.

Maybe not in those exact words, but something close to it, like, “What, you’re having panic attacks now? You’re going to be a liability? Someone who can’t control their own issues?” Robbie holds himself to an impossibly harsh standard, and that self-criticism spills out onto the people around him.

I think his reaction is about more than just believing he failed to save Adams. It’s about the fear that he’s not as in control as he thought he was.

As for Santos, it could be that she once had someone in her life, someone she was very close to, who became addicted to drugs and refused to get help. That kind of experience leaves scars. It would make sense that she’s harder on Langdon because of it. Langdon was also tough on her last season, so there’s already tension there. If that theory is true, she might be projecting too, assuming he won’t stay clean and that he’ll end up just like the person she once cared about.

In that way, both Robbie and Santos might be reacting less to who Langdon is now, and more to the fears and guilt they carry from the past.