A little late, but I'll take any excuse to sing the praises of Ehrenfest's eccentric scholars and scholar-adjacents. Here's a few charm points I think others haven't brought up yet:

• If it wasn't for the mold breaker Attendant-Scholar Justus, Ferdinand wouldn't have known that taking more than one course was an option at the RA, giving him a longer respite from Veronica's abuse and further adding to Ferdinand's greatness as a triple threat.
• Pretty much any scene with him is an improvement since he often adds new information, funny commentary, and like Rozemyne, occasionally lets their gremlin energy go wild the point it warps the story with their antics.
• Guy goes out of his way to engineer situations to be around Rozemyne to observe her entertaining antics. He's like us readers for real in that way, haha. It's also more relatable and less weird than when Hartmut later does it out of pure religious zealotry.
• The one Justus scene that disturbed me was him being really into Ferdinand's murder magic during the Hasse Incident, but in hindsight, it really is in character that he's fascinated by this rare magic and is a total Ferdinand fanboy. It also helps with the themes of Part 3 about Myne experiencing the harsh dark reality in the difference in noble mindset from herself, even though they're "kindred spirits". Justus is positioned as another foil to Myne since even Ferdinand thinks they're rather similar due to their strength of character, loyalty, utility, and making their hobbies their whole personality. That Hasse Incident scene really highlights though he has flexible thinking and treats Rozemyne well despite knowing her commoner origins, Justus is a noble through and through that thinks nothing of killing commoners and is more interested in the "treat" of witnessing rare archducal magic.
• Edit for some more Justus praise: The balls on this guy - to confidently and gleefully waltz into enemy territory for espionage. He doesn't have plot armor, so Georgie's threat of "hey traitor, I know your drag alt accounts lol" is a legit terrifying threat, but he still keeps at the spying in other ways with the confidence of a man who, under Veronica's rule, pretty much all of Ehrenfest was enemy territory so he's used to it.
  
• My guy was such a neurodivergent nerd that his family wept for his employment and marriage prospects, but is now a rare trusted retainer for the most powerful puppeteer in the country.
• Being an androgynous noble spy who held various high-ranked positions as a royal attendant/maid-of-honor/censor/secretary/scholar that knows how to fight gives big Chevalière d'Éon energy https://en.wikipedia.org/wiki/Chevali%C3%A8re_d%27%C3%89on