What it means by protecting is that the painting cannot leave their sight.
When he returned from that world that night, he must have come out of this painting. And at that time, the source fire leaked was Olusia's target.
Similarly, these source fires are not only needed by Aulusia, but all fire demons will go crazy for them! What's more, there are still humans coveting it, so they must protect this painting and send the source fire to them as soon as possible.
Fire is in your hands.
Chapter completed!