I just got to his highest approval rating.

I got a scene similar to this.

Hmmm.

This is rather unsettling.

He IS a person.

https://www.youtube.com/watch?v=xF3caGwGpJU

His identity is programmed, his memories written.....I would not forget that if I were you. The Institute does build them to be good approximations of human beings. Since you joined the institute he's unlikely to be a threat to you but then again you need to be pretty anti humanity to join the institute I think. I did nothing for the institute after first leaving it and kind of forgot about him.....some hours after finishing the game I wound up by the location I was originally supposed to meet him at by chance and was quite surprised to see this courser there.....then I remembered who he was. Oh well, one less threat to humanity.

I kinda don't want to watch that since I haven't gotten to that point with him yet and don't want to spoil myself, but I'm curious... I assume he says some things that can't be chalked up to his programming going 'if action committed good for Institute -> offer praise'?

It's basically programmed speech but with a bit more human-like cool flare like "holy crap" and says "I think" a lot and such.....but basically programmed speech. I mean they are made and intended to be able to easily pass for humans so they were made to sound more interesting than beep bop.

Hmm, yeah, those sound more like embellishments added to make his speech patterns more humanlike rather than any expression of actual personhood.

Remember the poster.

X6-88 drops all of the Robot Speak and says how he was scared you weren't going to be good enough, how you wouldn't live up to Father (who he had admired since he was a child), and that this was all a disaster in the making but you've earned his respect.

Also, he says [censored] and other cuss words when he feels like he isn't getting his point across.

Also, insists he isn't very good at making speeches.

But all this is actually in accordance with his purpose of ensuring the well-being of the Institute and its new Director, yes? The manner in which he expresses this may just be programming anyway. He's still in no way deviating from his programmed purpose.

Uh, no actually, not at all. The whole thing is about X6-88 dropping his usual robotic monotones and showing genuine emotion.

That, yes, the most inhuman Synth is as human as the rest.

Which surprised me.

But you be the judge when you get there!

Programmed emotion.......it simply means you met their expectations and are now accepted as director rather than just followed due to position of authority and that you are no longer looked at with worry and suspicion. Do you feel proud yet?

"All my life" =/= "since I was a child"

"The world will be better off once the surface dwellers die out."

Welp, the Institute's goal is clear.

Problem is that all the dialogue in the game is written by scriptwriters and all of the npc are handled by the same simple game ai so all emotions including your own character ones options are programmed.
You have to read behind the lines here.