Some people have outright said they picked their names. I don't know if any of the girls have mentioned it, but plenty of the guys said they chose their own names. Fulgur said he picked his because of lore, Uki based his on a song, Mysta chose his because it's a pun, etc. There have also been people who have been given names, like Kyo, but I don't know if the two people you listed are the latter or the former. I know Vesalius was an actual doctor or something so maybe that's where he got it.