What if we can’t see it because while energetic it emits less radiation and then will become brighter and hotter as it loses energy? Perhaps it even has reversed entropy too and becomes more energetic over time.
I don't think this would fit the evidence we currently have for dark matter. If it absorbed energy, then it would be much more visible and detectable, as it would often be blocking light and other radiation from objects behind it ... at least slightly, and that drop in brightness when dark matter passes in front of something would be fairly easily detectable. (Unless the effect was extremely tiny, I suppose.)
As far as we can currently tell, dark matter only interacts with the rest of the universe through the gravitational force. It doesn't absorb or emit any energy. (Except, perhaps, gravitational wave energy.)
Maybe it could work with antimatter instead of dark matter?
Involving antimatter really doesn't help make anything here more plausible.