Nachielus was the angel of Joy but one miracle he performed centuries ago started a tradition and he became known as Santa by humans. When the leadership team who are total jobsworths tell him he’s on reprimand for performing unsanctioned miracles and he dare too topside he’s unhappy . When Adam and Minos tell him to go topside and have fun that’s what he does and he meets Beck who’s dressed as and Elf for a charity and he’s waiting for the volunteer Santa. When Beck sees Nach he thinks he’s the volunteer Santa and he also thinks he’s hot and they hit it off immediately.  As with the rest of the series this is insta love which I’m not really keen on but as the books are funny and quirky I’m ok with it.