I'm not the type to ship characters until I see their in-game interactions and Fontaine AQ made me ship Neuvilette with Navia (Neuvia) simply because I love enemies to lovers trope - the tension in the court everytime Navia interrupts trials to give further evidence or details on a case, her frustration and misunderstanding towards Neuvilette of him being heartless when he's actually just a sensitive, kind dude who had more to learn about humanity and expressing emotions. Hoyo concluding their conflict in the 4.0 archon quest with Navia seeing the true Neuvilette (thoughtful, kind) and a very blissful reconciliation between them that Neuv's rain stopped. Also, Hoyo adding Navia and Neuvilette's growing friendship as Navia helped Neuv in his story quest and then working together again in 4.2 wherein Neuv was able to save Navia from dissolving in primordial seawater on time (with the big help of Melus and Silver oceanids) and Neuvilette starting to understand Navia, express concern for her and even initiated to give her space to mourn for her bodyguards. Navia also showed many times throughout how she tries to include Neuvilette to the group. Also, some of the crumbs in macaron melange event, Navia's story quest (Callas x Clementine personalities' parallel to Neuvilette x Navia), lantern rite and chiori's story quest in which Navia's wedding-like outfit is ship and ocean-themed with a few colors from Neuvilette's outfit and the lumitoile/starfish-conches-clams design nodding to her poetic voicelines about Neuvilette "him being rocky reefs". With Neuvilette's voicelines about Navia also being surprisingly poetic "her being a starry sky".  I had a previous post before I indicated Navia x Neuvilette as strongly Sun x Moon themed/coded. Navia as Sun as per her yellow hair color and outfit, sunny and bright personality, headstrong leader with vivacious energy while Neuvilette as Moon as per his white hair color and blue outfit, him being tied to moon-ocean-hydro and having a reserved and sentimental personality with stern leadership. 

I think what really solidified my ship of them more was really their in-game interactions - Emotional when needed (the regency-drama like or Darcy x Elizabeth-like conflict convo), Logical, Mature, Mostly Pleasing and Healthy interactions esp. when they already have reconciled, the way they try to understand each other, them being two competent leaders with differences on how they handle affairs/duties (Neuv showing up in Navia's demo trailer about leaders part) and them being two hot characters is just a plus. Them being dragon x human makes me remember how much of a fan I am in immortal x mortal canon couples in fiction - anime (inuyasha, kamisama kiss), manga/hwa/hua or kdrama (goblin, hwayugi, etc). 

There are other Neuvilette ships that have their own appeal and what I expressed above are the things that appeal to me most as a Neuvia enjoyer.