inter mundos exists as an almost-entity. a hairs-breadth below sentience. it has a permanent connection to io's brain, enough for it to perform the constant math that involves moving itself, its occupants, and an entire other building through time and space. and enough of a connection that it can draw on the deep well of io's magic. and it will only draw on io's. their blood is in the paint of the sigils, as well as ingredients that have a deep personal connection to them. suddenly and violently severing the link between io and inter mundos (destroying it) would be mentally devastating to them, and they likely would not recover, unless they were still in possession of enough of themself to slowly rebuild the shop (unlikely). but this is something io has told no one. to do so would be a massive show of trust and io is... rarely capable of that. it's an incredibly risky choice they made, but it was the only way to allow the shop full function in the way that they desired. inter mundos can defend itself if necessary. if io is not present, then it can't defend itself as well. if io is close, then it can absolutely utilize their mind to achieve a brief, malicious form of sentience and thought. and with its ability to bend time and space, reshape reality as it sees fit, and use io's power - it is very good at defending itself.