Will starring opposite each other in the tragic Rabbit Hole offer a new understanding between real-life couple Poon Chan-leung and Louisa So? Winnie Chau is there to find out.

There is one particular question that interviewers should carefully eschew – or astutely rephrase – when talking to stage actor Poon Chan-leung and his long-term girlfriend Louisa So, who is perhaps more recognised as a TV actor. Oddly enough, it’s Poon who brings it up by the end of this interview. “Some would ask: when both of you work together, would you two [at this point So bursts out laughing] quarrel?” Poon repeats the frequently asked question nonchalantly. “This question is so annoying!” So adds quickly. “Quarrels are good,” they affirm one after another. “It means communication,” says Poon.

Inside Hong Kong Repertory Theatre’s rehearsal studio, there is a spare chair between Poon and So. As our conversation proceeds, it becomes clear that the main reason they are cast as the married couple in David Lindsay-Abaire’s tragic play Rabbit Hole isn’t so much about their offstage relationship. If anything, it is their ability to maintain a respectable distance from each other.

The deliberate anti-melodramatic quality of Rabbit Hole, according to Poon and So, makes it a poignantly accurate portrayal of bereavement through the story of Becca and Howie, whose four-year-old son has been lost to a traffic accident eight months earlier. As actors, the fun part of the rehearsals has been complying with the script’s strict staging and acting directions by avoiding physical contact as much as possible. “For instance, [the playwright] advises against any attempts of unnecessary embraces. Neither are [casual] bodily touches nor additional tears allowed,” says So, who’s totally in favour of these rigid instructions. “If he didn’t write them out, directors and actors would habitually make it very sentimental and melodramatic with all the crying and sniffling. But this play is exactly not that.”

“When we rehearse, it’s easy to find certain parts moving, which is normal. Moving because those lines or that character has moved Poon Chan-leung as an actor,” admits Poon. “But the play isn’t trying to express that kind of emotional stir. That’s a temptation in acting.” His partner can’t help interrupting: “That’s right. That’s right.”

Poon is no stranger to understated acting. The low-profile actor, whose name is invariably on his counterparts’ ‘my favourite actor list’, exudes a dispassionate disposition, leaving little traces of Dr Faustus, Uncle Vanya’s Mikhail Lvovich Astrov or the heavily-accented eccentric explorer in Bun in the Cave. The few instances Poon loses his cool during the 40-minute conversation are when he laughs at So’s words or, when he is challenged by her mischievous remarks, vice-versa.

Regrettably, Poon, too, is acquainted with bereavement in real life – his parents have both passed away. In fact, his grief over his father has given birth to his directorial debut, the autobiographical An Ordinary Man, which was staged at last year’s Hong Kong Arts Festival (So was in the cast). Nevertheless, Poon thinks the death of a parent and that of one’s own child are worlds apart. “[We’ve] discussed it before, as if it were our child… facing his or her passing away would seem something very unreasonable – as if it were an absolute impossibility. Yet, if your parents’ death preceded yours, somehow you could take it,” says Poon. “Thus, that pain and difficulty [from losing a child] is, to me at this moment, unimaginable.”

Then what if this play came later in their life, when they’re married with children? Would they be willing to take up the tragic roles all the same? “If I were married with children, I think my portrayal of the character could be further enriched,” So replies matter-of-factly. “When it’s a play as good as this, it’s impossible not to accept [the role].” As for Poon: “Even if I had exactly the same trauma, I guess – but this may just be an offhand response – I would do it regardless.”

So they should. The two, who first met 20 years ago when they studied acting at the Hong Kong Academy for Performing Arts, are more often spotted sitting next to each other in the audience than seen co-performing onstage. Despite So’s packed schedule as a TV star, she squeezes in time to see films, plays and even TV dramas with Poon and they exchange views on the acting afterwards. “We actually have a lot of common subjects and share many points of view. I think this is a blessing…” So trails off, as if momentarily melted by her own words.

Even when asked if they have any divergent thoughts on acting, their responses are nothing short of dramatic: “Divergence uh? There should be none, I guess,” Poon chuckles at his reply. Before he can continue, So declares abruptly but matter-of-factly ‘he is more capable than I am’. “Don’t say that,” Poon responds, just as promptly. “The divergence is that he is more capable than I am,” So repeats, giggling. “That’s not what ‘divergence’ means!” Poon gives up, lovingly. In fact, there isn’t really room for that ‘annoying question’.

Rabbit Hole 心洞 is performed at Arts Centre’s Shouson Theatre Mar 17-Apr 7, in Cantonese with Chinese and English surtitles. Tickets: 2734 9009; www.urbtix.hk.