Is Duvall associating what MC used with something she's familiar with, is she correct in that MC stumbled upon null magic, but it's a different source than how Duvall knows of it, or has he found a portal world that Duvall is already familiar with? I still think it would be more interesting if Duvall allied with MC. Her main reason for being hostile was because he threatened her position in GAR, but with GAR having essentially collapsed, there's no such position to speak of. She no longer has a compelling reason to monopolise space magic, so if she and MC put their heads together, her experience and foundational understanding of space magic with his innovation would produce results for more interesting than anything either is likely to achieve on their own. It also just occurred to me that if MC has a similar lifespan to archmages given that he essentially is one, will he not outlive Lucy by a rather long time?