In chapter 198, the demon said that Asta’s demon should take over Asta’s body quickly if he doesn’t want to die along with it. This got me thinking; why would Asta’s demon die if it was solely in the grimoire? The grimoire was fine for the 500-something years between Asta and Licht, and Licht “dying” didn’t seem to affect it either. Now, for it to die along with Asta, it would have to be at least partially connected to him. It could be that using the grimoire is akin to using the demon, and that might fuse Asta and the demon to a point of eventual inseparability. If this were the case, it would make sense for the demon to die along with Asta if Asta were to perish. It might be that when the witch queen accelerated the flow of power in Asta’s blood, it further connected him with the demon, which was why he was able to have a chat with him. Using more of the grimoire (and by proxy the demon’s) power might deepen this connection. I seem to recall a sword that Asta just got, which was mentioned to have a price for being used by Droit? The consequence might end up being completely fusing the two, to where the demon is finally in Asta…and can talk more freely and possibly even take him over.