Rex doesn't really care about this holiday. Love is not bound by time nor space, and especially not an irrelevant positioning of the Earth on its loop around the sun. And he's dealt with enough actual gangsters to find romanticising them to be somewhat distasteful, but not enough to be offended. And unlike Halloween doing the majority of the magical and mechanical work to make the whole thing operate wasn't especially interesting, or challenging. Worst of all the clothing is boring. Rex has always been of the opinion that a suit is basically an attempt to turn a man into a sexless rectangle. He's at least made sure his has the Bulgarian embroidery he's fond of. All in all, Valentine's Day is a bottom tier holiday, not to be used competitively.

However...

The theme happens to incorporate amongst his most favourite musical genres and absolute favourite dance style. He's also incredibly good at it. He's quite clearly going to spend most of the night doing dancing- a lot of it slips back and forth between the 20s and 30s, but it's all the wildly energetic sort of swing that it don't mean a thing if you ain't got. While more than happy to dance alone when the Lindy Hop or similar is appropriate, he offers to dance with or teach others to dance. Student, Faculty, spirit, unusually large and intelligent mustelid, it's fine. He's even sometimes different heights- a spell to shrink to a more appropriate size for a partner is pretty easy for him.

And when music that doesn't fit the theme plays, as it inevitably must, it's like a light switch. His small smile snaps off, Rex slings his jacket over his shoulder and walks away from the floor to people-watch instead.

Of course, this attitude and aptitude makes Rex pretty popular with the spirits around and occasionally ends up with a more friendly version of a past visual. Just a buncha happy spirits all danced out hanging off him as he drinks something boring at the sidelines.