Damn Remu, you just made Azuki's mega cope so much worse...
@adel91 Jumping off from what rainbow8 said, Niji is essentially writing a fantasy between herself and Remu. Everytime Real Remu does something that follows her Story Remu's actions, She seems to get happier like shes one step closer to realizing her 'fantasy come to life'.
But whenever Real Remu 'deviates from the script' so to speak she gets this dark yandere-esque vibes to her like she needs to interfere so that Real Remu goes back onto the 'correct story path' that leads to Niji herself being the love interest like in her story and not someone else.