The shard of dream / that you gave me / lurks within the endless night (Aria, Kalafina)
Perhaps her mistake was that she had too much faith: not in god, and not in the people that wore rags like she used to and would slit her throat to survive another day; not in the aristocrats that looked down on her like she was nothing more than an intruder in their world. Casca had believed too much into the small world made of tents and yelling men, that calm that remained unbroken battle after battle, and the certainty that things were fine as they were, even when she already knew they wouldn't stay the same.
There were things that she had thought weren't worth thinking over, that there was no meaning other than 'we are comrades' and 'I should accept him because Griffith did' to every word or gesture that wasn't too harsh and that she had directed at Guts. Even now, Casca didn't really understand, couldn't find proper words to describe the bittersweet sense of panic that had taken over her, but she was finally able to see, at least, that she had made a mistake somewhere, that she had underestimated something she still didn't know the name of or, maybe, it was herself that Casca had overestimated instead, and the thought, while vague and confused, made her feel a bit sick. Remembering herself, angry and tired, yelling at Guts, don't act like a mad dog, think about your companions, she felt a bit like a hypocrite.
Her mistake was having too much faith, and Casca had too much faith in Griffith too, sometimes: even if she saw, even if she understood that he really was still a man born with nothing.
Casca pushed, and the door to his room was slammed open, against the stone wall with a terrible noise that echoed throughout the hallway.
Griffith was hunched over thick volumes she had always thought would be too boring for her, although just the thought of telling Griffith the truth (or openly agreeing with Guts) made her cheeks burn with shame.
"Casca…?" Griffith was still dressed: pretty elegant clothes complimenting his face, and skin and hair, making him look like a small star. Griffith was still dressed: he hadn't slept at all.
Casca had too much faith in Griffith sometimes, so she didn't hear anything in his voice that wasn't the usual, quiet gentleness he used when talking to her.
Casca didn't hear that feeling that vaguely resembled fear, that stemmed from the acknowledgement of 'this time I could not make it', in his voice. She didn't see it in his eyes, shimmering dully like ice.
Casca couldn't know back then: something about her face, something in her expression, already gave away all the regret, the fear, the frustration, the anger, and even if Griffith sometimes couldn't read himself at all, he could read people all too well.
Slowly, stiffly, expressionlessly, he got up and faced her.
"What happened? Casca?"
"He… Guts is…! Guts is going to—"
At that moment, Griffith felt something like ice cold water, a poisonous slime filling up his stomach and seizing his heart: it kept filling and filling him, up and up to his throat and then his mouth, until he had to clench his teeth, thinking that if he didn't, he might end up throwing up.
It was all the words he had always refused to speak or even think; it was the longing that had become, at some point, more important than the dream, that was starting to rot, now, like an untreated wound.
But sometimes Griffith - not too unlike Casca - had too much faith in his world changing only according to his wishes. He believed too much in himself when it came to deciding what made him content and what mattered the most.
And at some point which would always be too soon for someone like him, Griffith - though he didn't know, couldn't, wouldn't see it yet - had started to believe too much in Guts.
"Please, hurry, he will listen to you! Surely!" Casca grasped his hand, tugged, thinking, so cold!, and finally saw the ice in his eyes, finally remembered: Griffith too is only a man.
But it was too late to take those words, that responsibility back, away from Griffith's shoulders, and no matter what, she didn't want to let go of him or Guts.
It made her heart sting, then freeze, when she saw Griffith, face still blank, grabbing his sword before walking into the hallway.
"Lead me," was all he said, and Casca nodded.