It's funny how only 2B ever calls 9S Nines through the whole game. It's almost like she gave him the nickname somewhere before.

I came away with the impression 9S still loves 2B even after learning the whole truth. His anger seemed directed towards the lies and deceptions that put them in this endless cycle of conflict. He's still mourning for 2B well after her death. The game also gave plenty of information to 9S to understand 2B cared deeply for him as well. 2B carried out her true duty as 2E, but it was very clear she cared deeply for 9S and could not stand to see him suffer or be mistreated, showing more distress seeing Adam briefly torture 9S than her own horrifying last moments, which ended in relief from a final glance at 9S.

When 2B died I was literally in denial till the last scene in the entire game. I loved her so much I couldn't accept that she was dead ;-;

This is why ending E is the best ending possible for them... people call it bittersweet, but it was the most optimistic and fulfilling thing I've seen in a while.

I always thought the reason 9S was "enjoying" killing the 2B models was linked to androids being programmed to find pleasure in battle. (It's explained in one of Jackass' quest lines). It would also kind of explain how 2B kills 9S kinda intimately. Perhaps it's the only way they know how to express their feelings. For them, combat is quite strongly linked to desire / maybe love.

"Sheesh, why is she the one screaming emotions are prohibited yet so emotional over the death of someone she just met? This is stupid, the game is too anime nonsense, i'm out!" - lots of people on Route A without knowing what's awaiting them.

This is the game where all the characters you love go mad,

To be honest at the moment were he said "Dont worry 2B I'll kill you." People usually saw that as "I'll kill you because I hate you." But what I think the creator wanted us to hear is not "I'll kill you." but the "Dont worry 2B." The reason is the only way for 2B to be happy is to die. So what 9S did was kill her because he loved her and didn't want her to suffer any longer. Thats why in the end when he puts one of the dead 2B hands on his cheek I think its because he feels happy that shes dead.

Oh my god.. I just realizes that the hole on the castle at 0:45 is heart shaped.. MADE ME SHIP THESE TWO BUTTS MORE.

Remember the theme park mission with robot Romeo and Juliet killing each other? Yeah. Yoko Taro was being subtle by not being the least bit subtle. There are hints like this throughout the game.

the scene when 9s finds 2b's ship and her last recording is truly heartbreaking ....

What I think is really messed up is that during the time trial quest with jackass she discovers that androids experience the similar human emotion of love with they fight. So when 2b had to choke 9s would it be right to say that she had to suffer both the enjoyment and frustration of killing 9s? (not to say that's why she killed him in somewhat sexual manner) That would be truly sad, to experience love or happiness when you do what you hate the most.