William Campbell is superbly cast, bringing off a memorable combination of sophistication, naiveté, and very very angry. (This performance is better than his less flamboyant Koloth though as there the repartee between Shatner and Campbell is deliciousness rarely matched in the series.) Given the ethereal nature of his kind the only substance about Trelane is his hyperactive personality, and to convey that consistently (without spoiling the reveal) takes a great performer. The items in his collection are odd, especially the incongruous appearance of a salt vampire, but the castle crannies are as pockets to a child that creates planets for sport. There's just no telling what might be in there.

After unusually heading an away team (equipped with unique breathers to take off) McCoy does little in the show. Faring better is Spock as continual irritant to Trelane (objecting in terms relished as ill-mannered!). Ample screentime is shared among the rest, from a harpsichord playing Uhura (taken as conquest, no doubt) to an indignant Honorable Sir, from Michael Barrier as DeSalle at his most aggressive and impatient to Venita Wolf as Yeoman Ross, hurried offstage after one interrupted dance at the ball.

The parents (in a special effect unaged by simplicity) are kind to Captain Kirk as human parents might console a strange animal found tormented by their offspring. There's a credible line of continuity that Trelane grows up to be Q in TNG, that might explain the latter's fascination (interest?) in humanity yet there's still something not quite right in the timing. The script is clear that 900 light years intervene between Gothos and Earth. Since Trelane refers to figures from the early nineteenth century that would seem to place TOS several centuries ahead of where scholars conventionally date it. Far more confusing, albeit granted Kirk is an expert at ladies and dipping: What on Earth (or Gothos) is an inkwell?