I also believe you have a M-F pair, Alissa. Our "pair" of reds acted the same way.
We've kept
Inimicus sp. stingfish for close to five years now. We've kept
I. didactylus and still keep
I. japonicus, which was our first goblin.
We feed it 3x a week, along with our other "things with stings", and it gets a varied diet of SW fish flesh, shrimp, lobster, squid, bivalves, etc. and feeds from a "stealth stick".
They aren't the most active fish in the world, but they do have their own personality, and are interesting-looking fish, to be sure.
They are indeed venomous, and have a much more potent sting than lions/scorpionfish, more on the order of the waspish in terms of toxicity. However, they aren't deadly by any means, and the only way I can see anyone getting poked is by putting their hand directly on the fish.
That being said, they're pretty easy-care fish. You'll need substrate for it suitable in depth and grain size for it to bury itself, as it will spend a fair amount of time like this:
They're definitely one of my faves...how can you not love a face like this?