Just a random update: Choi Oppa has roommates in his ten gallon: a gold mystery snail (that he has completely IGNORED) and two ghost shrimp. :)
When we put the ghost shrimp in last night, he chased each one all of once, nipped once (because one of the shrimp was hiding out in his favorite corner of the tank) and... that was it. We gave him some food and he left the shrimp alone after that.

The funny thing is, he didn't flare at any of them.
He DID discover, however, that he can see his reflection under the filter, so he spent about two minutes flaring at himself. Because he's a younger fish, he has to try especially hard to flare. He'll sort of half-flare, then strut around the tank sulking, before coming back to do a full flare. Unlike my past bettas, who could show off a full flare anytime they wanted, Choi has to hold his beard out to keep a full flare displayed. Otherwise, it's always a half flare.