![](https://pic1.mangapicgallery.com/r/avatar/e0/u694155_50x50.jpg?2)
In the novel, he hated anyone from the government because he was trapped and FL was part of that government. He fell in love with her over time because of sincerity, but he was extremely worried that the government was always watching. He knew the government would use FL if they found out he cared for her. That’s why he made sure she was always near her and ignored her to protect her. Was it cruel of him, yes, but he had his reasons.
I'm not trying to defend Ciel, but I'm giving him the benefit of the doubt for now.
I don't know, i think there's more to his backstory. He's a coerced war dog trapped in korea, and my theory is that they, the government and that fake ass bitch saintess, forced him to bond with the FL so that he can't get back at them since FL will be his only guide.
That's why he's paranoid every time that Fl goes out without telling him and can't fully trust her.
And about his possessiveness, I'm threading this like how I thread an Omegaverse story. Possessiveness and Obsession is a thing that you can't fight and more like an instincts. You just have to accept it since it looks like every esper is like that.
This is my theory only.
If there's a light novel, please do spoil me