Felix Caelus

When he says it like that, Jim feels foolish for asking if it was Felix's flame atronach at all. He'd only been thinking about the burns on Felix's body, about the light she would have been able to provide down below. The atronach is a being of destructive fire though. While she doesn't burn what Felix doesn't ask her to Usually there would have been too much risk. Books are flammable and her hands would incinerate them surely.

But the other atronachs, the familiar, they don't have hands at all. To try a new summon, beings powerful enough to serve Princes directly, in a place like Rielle when Felix was already too shaken to venture down himself...

Felix admits to nothing but Jim remembers all too well the mangled state of his armor. Where it looked to have taken a heavy blow. Not by fire nor an explosion but by a weapon. If Felix didn't venture down into Rielle's deeper lairs then he could only have been attacked by the dremora itself.

"How...long is it going to stay summoned? The dremora?" It made the journey over between planes. It attacked his husband. It's not bound by Felix's control. Lucky indeed that Rielle is secluded far from any nearby towns, but still.