On the contrary, I think Shiki is perfectly sane. There hasn't been a point yet, perhaps because I can control his choices to some extent, that I ever felt like I wanted to leave his perspective for the sake of disagreeing with it. I never felt like he ever lost his mind. All I ever saw was that he was suffering from his experiences, with either the option to keep going, and be responsible for his situation, or give up, and try to run away.
In the case of Arcueid, honestly, when I was asked what I thought about her at the restaurant, I called her selfish. When Shiki killed her, I was expecting, just as he was, that she waited, and chased him with the sole purpose of revenge for killing her. I was thinking the scene that would follow would be either begging for his life, or killing her again. Instead, she's lost interest in revenge, and asks if he's sorry. Well, of course he's sorry. He didn't mean to kill her to begin with, just whatever was inside him made him tick, and want to kill her, even without his consent. She asks Shiki, or in the game's case, me, to help her. Of course, I saw it as a way to make up for what happened, so I agree. Then almost every scene with her after that, is her being a complete idiot. Not only is it hard enough to kill supernatural beings with a fruitknife while being chewed on, but she gets hurt as well, and basically declares that she's going to go attempt to do what she said we'd do together, declares that she's probably going to die trying, and simply leaves it at that.
Child's mentality or no, the constant crap she put me through caused me to get an ending where Shiki simply went back to school, and never saw her again as if nothing happened. THAT ending, with the simple words, 'are you forgetting something?' made me think, 'No, I'm not forgetting anything. I'm hurt, my chest has been bleeding for no reason, my brain feels ready to explode, and the girl who asked me to help her doesn't want my help anymore, she wants me to go away. I can't find her, I waited at the park at the time she made me promise to wait, I waited even an hour after that. She's wants me to be gone, so it can't be helped.'
To me, that ending was better than Arcueid's True Ending. It wasn't a satisfying conclusion, but then again, her true ending wasn't either. After going through all of that, she dies in my arms, I think she's dead. Even that would have been fine, with it ending with Shiki returning to the mansion and living happily with his sister, Huisi, and Kohaku. BUT, she reappears. Oh, joy! I think to myself. She's fine, revived somehow. But then, just as soon as she reappears, she goes away, saying she's going to go back to sleep, likely for a time beyond my natural life.
Absolutely. Terrible. God, that was horrible. And I even agreed with Shiki, 'Please, stay,' we both thought. But nope, just like all those times before, she vanishes. That ending, with Shiki simply saying goodbye, was the only moment where I didn't agree with him. Shit, I've chased after her, almost literally through Hell, just to see her. Letting it all go, and just going back to the way things were is something I wouldn't be able to accept. Wherever she's gone, it's still gotta be on planet Earth. And that means I'd search for her, even if it means giving up on everything else that's around.
So, that ending left me irritated. I wasn't satisfied. Playing through a second time, in the process of it, I said to myself, "Fuck you Arcueid," when she asked me to be her 'shield,' as she did before. Of course, she used her mystic eyes, and forced me into it anyway. There's no way I'm going to try for a second ending with her. I just don't like her. Ciel's my next attempt, since Akiha's a mean bitch, dragging me all the way to the mansion, and treating me like she hates my guts, and Huisi is just plain creepy. And with what you said about Kohaku, I'm having doubts there as well. I actually thought something nice might happen with someone who seems like the brightest of the bunch.