Lucy and Lucius were still regular humans, but they were really close to becoming High Humans. Darian chose to hold off on telling them the more dangerous stuff for now. It was better if the two of them focused on the trial without too much pressure.
That's why Rhea stayed hidden from them. Darian taught Leander and Veyle the summoner support techniques he'd learned in that other universe.
It worked perfectly. Now, Darian had made it a priority to collect every single technique once he went back to that place. In the end, both spirits could stay hidden inside their summoner's body, and only come out when needed.
Their rune could hold onto both black and white power, letting them form a physical 'body' using that power when the time was right.
That entire clan—now just five people—started eating like kings, all amazed by how good Lucius was in the kitchen. Well, almost all of them. A quiet girl ate slowly and without much expression.