THERE IS NO SUCH THING AS A GOOD NICKNAME
YOU'RE THE ONLY ONE WHO CAN CALL HIM CLOUDY
THE NICKNAME MEANS JACKSHIT WHAT MATTERS IS THE CONTEXT BEHIND IT!!!
also, if you're wondering about the "-san" thing, i did some research (yeah you looked at one google page you slut)
so basically, san is given to someone you respect. i felt like it would fit because evergen is the team leader, who dusk respects, and viane, as dusk learns about plants from her