Tenma's pet names for Johan reserves only during sex or other intimate moments. His are just standards: baby, honey, are the most common ones, less common sweetie, very RARELY 'my sweet Angel', and when he says this, it's mostly when he makes mistakes over trivial domestic stuff, Johan gets upset or shuts him out and he tries to woo him back, but bc this is trivial stuff, Tenma also says this w/ playful intent, hint of mockery. Johan knows when he calls him that, it's mostly Tenma trying to joke around and lighten the tense atmosphere. Also, I have posted the 1st version of this here: https://x.com/deNamelessHuman/status/1927306388490874977?t=cVCLnt0C4f1670_J3Vql7Q&s=19

Jan Suk will call him pet names at every single time is possible, he's just that kinda simping guy: Babe (almost all the time, he rarely even calls him Johan anymore unless they are outside in public with many people around)
Jan Suk's other pet names for him are all obnoxiously cloying sweet and the trademark is everything tagged with 'my' to assert every time who Johan belongs to
As in: my angel, my pretty flower, my sweet princess, my cute little kitten.

Roberto calls him pet names also mostly when they are together, in appropriate times, tho he tends to use them more than Tenma
As in: my Queen, my little princess, my sweet Angel (and he's being serious when he says this, unlike Tenma), the king of my heart, my king, baby, babe, my sweetheart