I firmly believe that Claude never sees/acknowledges Athy as his duaghter until she openly shows her true self and emotions—the first event, being when he publicly humiliates her.
Up until then, Athy had always been a constant reminder of Diana, but not once had Claude ever been reminded of himself. Athy copying/imitating Jennette’s mannerisms inadvertently made her the perfect Diana replacement—someone who will be by his side no matter what harsh words he says, no matter what odd or cruel things he says or does, someone who will love him blindedly and without question—those were all the things he perceived from Athy, and all that Athy would allow to slip out in front of him. She upholds this persona even in front of Felix and Lily to an extent, garnering positive attention and stirring protective emotions by behaving cute and lovely from when she was a child. A lot of her quips and annoyances remain as inner monologue, while Athy is spouting airy and sugar coated words. Claude doesn’t see himself in what she does at all—Athy has always been Diana’s child, but not once could he ever see her as his child.
Until the Public Humiliation event—denouncing to all that she’s a fraud, a fake, and that should she show herself before him he will kill her. That’s Athy’s last straw, among the stress and turmoil of losing years of what she’s worked for and back to square one with a bloodthirsty maniac, she has no energy to keep up the lovely princess facade. So when she’s disrespected, she lets it go—her true face, one of contempt—and that’s when Claude with or without amnesia can finally see it, without the clouded shadow of Diana—that Athy looks like him.
And it’s after the amnesia arc when I notice the frequency of Athy’s inner quips lower. She still quips and complains and is sarcastic in her inner monologue and narration, but she’s no longer up keeping the sweet persona she did previously—or at least, not to its extent. She’s shown a bitter side to her, one that goes against Claude’s rose colored Diana vision. Her attempt to jog his memory post runaway arc by reciting the “flowers bloom in my mouth” line after drinking tea yielded little to no results. Acting like Jennette or Diana isn’t gonna fix him, so she stops/does it less.
I dare say amnesia Claude saw Athy more as his daughter than pre-amnesia Claude. The memories of Diana are mixed up and fuzzy because of the state he was returned to, so he can’t rely on those as comparisons for Athy as much as he did previously. So when he sees Athy, and the most ingrained memory being her face of contempt and frustration—he can only have himself to compare her to, so I find their moments during amnesia arc much more compelling than pre-amnesia, where Athy was still forcing herself to be sweet and loving. Things like helping her study, helping her understand magic—those aren’t things Diana could do. But he has a past in which he couldn’t study or gain education as easily as his brother—and he likely had to teach himself how to use his own magic as well. This trait, this moment of vulnerability Athy has, that’s not traits from Diana—they’re traits from him.
Pre-Amnesia Claude can only see Athy as Diana’s daughter—perfect, lovable, adoring and good at dancing and her studies. But Amnesia-Claude can only see Athy as his daughter—bitter, anguished, magically talented but has difficulty understanding how to make use of it, and first and foremost the runaway arc has set in his mind that he forced her to fend for herself in a world she wasn’t prepared for.
People may have liked pre-amnesia arc Claude, but amnesia arc Claude is where he actually sees her as his daughter. It’s the ugliness that makes them family, not the sugar coated sweet teatimes. Claude knows he’s a horrible and disgusting person, and it’s in Athy’s own imperfections and ugliness where he actually sees himself.
The readers and fandom wanted tea time dates completely missing the way that those tea time dates were the biggest burden between them—it’s where Claude remembers Diana best, and this sees himself and Athy the least. If the fandom truly wanted actual displays of family rather than projecting his dead lover onto her daughter, going on dates for heaven’s sake, they should’ve longed for the bitterness and the ugly—because that’s when their blood relationship actually comes to light without any pretense.
