Picture it: You are melting into your seat while taking in a so-so Rosenkavalier. The night is warm, the dinner was heavy, and Baron Ochs's humor is beginning to smell of Viennese coffee left on the burner too long — when suddenly your attention is delightfully rekindled by the sly machinations of those roguish intriguers, Annina and Valzacchi.

That secondary characters could so deftly seize focus is not unusual in opera. How many a standard-issue Tosca is enlivened because the Spoletta is such a fascinatingly nasty little guy? Or how often do we wander into the lobby after our umpteenth Bohème smiling at poor Alcindoro's fit of apoplexy at being stuck with the bohemians' dinner tab?

These are opera's scene stealers, the character comprimari who delight us with meticulously crafted bits of human portraiture that lend the operatic art a special theatrical spice.

Houston's Alcindoro is Gwynne Howell, doubling the old roué with the role of Benoit in Bohème as well as offering his peerless Old Dansker in Billy Budd. Having exercised his extraordinary interpretive skills onstage for 40 years ("The voice is willing, but the legs are sometimes weak," he jokes), the lyric bass cautions that the brevity of these assignments hardly translates into an artistic cakewalk. "These little roles are, in fact, nightmares, because they are very small, and very detailed — yet if they're too detailed, they don't fit. And there is no redemption, because they are over in a flash; if you bend down to pick up your program, Benoit is out the door. I am as demanding of myself as I would be if I were singing King Marke or Fiesco or Sachs. If it's easy for the artist, I think there could be something missing."

Jon Kolbet agrees. Kolbet is a character tenor, or Spieltenor, a specialization rooted in the alternating sung and spoken text of German Singspiel, of which Mozart's Abduction from the Seraglio and The Magic Flute — in which he will sing Monostatos — are glorious examples. "Monostatos is a chameleon," Kolbet reflects. "With his minions he wields a heavy hand, while with Sarastro he becomes completely obsequious. His aria (the pianissimo, rapid-fire "Alles fühlt der Liebe Freuden") is a tricky little number. Pianissimo perhaps, but it's got to be heard in a big house. The tessitura of the role sits quite low and the range of the aria is extremely small, yet it reveals much about Monostatos. The other challenge is the dialogue. It needs to sound natural and idiomatic, and without amplification must carry in the house."

Mention of dialogue reminds us of a handful of pivotal characters who make a singular impact, though they warble nary a quarter note. The Abduction from the Seraglio's Pasha Selim may not sing, but he is often played by a handsome actor whose sonorous elocution practically oozes manliness. For that reason, any number of sopranos have been challenged in mustering more enthusiasm for Belmonte, the tenor hero. Richard Spuler definitely has velvety vocals, but cautions that in director James Robinson's Oriental Express mounting, Selim is not your typical cardboard stud. "It's true that the Pasha calls for a dashing figure, but here he's also suave, debonair, and sensitive to the ways of Western culture. These aspects add an entirely new dimension to Konstanze's attraction. In his attempt to win her over, the Pasha seems willing to learn from her, and she from him — which makes their parting even more poignant."

Donizetti's comic masterpiece The Daughter of the Regiment offers two plum character assignments for actresses of both singing and speaking variety. Anyone who has seen Ewa Podles as Azucena (a performance part bel canto delicacy, part slasher movie) can attest to the exquisite Polish contralto's gift for theatrical flair; HGO has scored a coup in having her undertake the opera's Marquise of Berkenfield. In an interesting counterpoint, she sings Ulrica for her HGO debut in Verdi's A Masked Ball, which is being performed concurrently with The Daughter of the Regiment.

Daughter's non-singing Duchess of Krakenthorp has proved a romp for opera and Broadway divas alike — Ljuba Welitsch and Bea Arthur are two of many who come to mind. Houston's Duchess is a diva of a different sort: singer, turned manager, turned dynamo artistic administrator Diane Zola. Initially stunned at General Director Anthony Freud's suggestion she tackle the role ("How many drinks did you have at dinner?" she asked), Zola relishes a shot at infusing her daily routine with some comic escapism. "Sometimes people take themselves too seriously, and what's the point? This is opera, this isn't real life — this is letting people go someplace else and enjoy!"

An organic emergence of characterization is crucial. Zola notes her interpretation will largely depend upon her interaction with Podles. Gwynne Howell prefers to imprint the music firmly into the throat, then approach dramatic matters as "a clean sheet of paper, because if you arrive saying 'I do it like this' and see a look of horror on the producer's face, you're pulled apart before singing one note." Kolbet explains, "There are myriad options, and experimenting is one of the most exciting parts of being a singing actor."

The ultimate appeal of these roles may well lie in the obvious joy their interpreters bring to them. "It's amazing to work with such terrific artists," Spuler enthuses, reflecting on first hearing his Konstanze, Elizabeth Futral, in rehearsal when he performed the Pasha at HGO in 2001. "When she started singing, I think my jaw must have dropped to the floor. I had to pull myself together and play my part while still marveling at what she and the other singers did." Or as Kolbet wickedly observes, "I never get the girl, but I do enjoy trying to make it harder for 'the other tenor' to get her!"

"You can tell the quality of a company by these secondary roles." Zola observes. It's true. These delectable artists who warm our hearts with their genial mirth — or break them with a trenchant poignancy — are among the lyric theater's finest graces.

"Being a character singer is a wonderful thing," Kolbet summarizes, "Without us, how boring it all would be!"

Mark Thomas Ketterson is the Chicago correspondent for Opera News. He has also written for Lyric Opera of Chicago, USOperaweb and Chicago magazine.