I love how names work in Sanders Sides because we already know that a side revealing his name is a HUGE sign of trust (hence Virgil and Janus taking longer to reveal theirs) but there's also something about how they finally have something to be called that actually fits them.
Like every side starts out with one simple word that defines them for a while, like Logic, Creativity, and Morality. But once c!Thomas is able to see that they're more than just that one word and starts to explore what they are beyond that title, they get a real name.
Remus revealed his name almost immediately because he can't really be defined by one word in the first place. Sure, there's "intrusive thoughts" and "dark creativity", but he's also morbid curiosity and just in general a lot of what c!Thomas represses. They call him the Duke because he doesn't have a quick descriptor, and because he can't be so easily defined, he needs a name so that we have something to call him.
With Janus, we learn his name once he leans more into his role as self preservation, and what he is beyond "Deceit", which takes a while because obviously Thomas and the "light sides" only really want to see him as Deceit, and can't fathom that he's anything else. Only when we start to see the other aspects of him, and when Thomas starts to embrace those aspects a little more, do we learn Janus's name.
And of course, for Virgil, he revealed his name after the group realized that he's much more than excessive anxiety, he's also just caution and a bit of instinct in general.
Idk it's 11 pm and I don't have a whole lot of thoughts on names because this makes sense as is to me but I love this a lot