The fact that you just see the whole process, how much Albus is sacrificing and preserving, just to save this one girl. The fact that he knew her as the Demon King vessel first before truly getting to know her as an individual and appreciating her existence as an individual and cherishes her, that he would turn the world as many times as he needs for her. It just makes it all the more sweeter and tragic. He spent more than a century, going on the same adventure and doing the same tasks, to the point he memorizes it from the back of his hand, if only for a glimmer of hope to save her. Even if the whole world sees it as futile and meaningless, even if Fiona herself sees her own sacrifice as noble, Albus instead never wants to accept it because he sees meaning to her life and existence, and will do anything to keep it alive, even if it's to sacrifice himself.
Which I think part of this fondness comes from how he sees Merida in her, and how his worldview is influenced by her ideology on wanting the world to be a happier place. Which is why he believes that him saving and protecting Fiona is what would truly fulfill it.
I guess I'm in a little sentimental mood but this is definitely one of my favorite chapters in this whole manga.
