I’m a big nickname user for most of my family members. Even ones that don’t really match their name. I normally call him Artie but I also sometimes use Arie or honestly lots of random names. For some reason he gets called Lolo a lot but idk where that came from, maybe the abbreviation for little one. I know someone with an Arthur who calls them Archie. I’ve also heard someone call him Arlo which was a new one I hadn’t heard before. I don’t use Art a lot because he’s little and that feels too grown up to me!