One of the most redeemable qualities in any musician, and especially rock musicians, is restraint. Whether applied in matters of personal style (use the reliably gaudy Bret Michaels to reference its opposite), substance abuse, singing, or arrangement, moderation and self-discipline can, at once, make an artist likeable and his/her songs memorable. Many would argue that restraint is the antithesis of Rock n’Roll, especially for a post-punk artist like Peter Morén -– better known as one-third of Swedish pop-punk group Peter Bjorn and John. But the majority of music’s greatest contributions (think of the enduring simple melodies of Bob Marley, Lennon/McCartney, or the oral traditions of each one’s foundation, folk music itself) have an undeniable underlying simplicity — which consequently leads to universality. On a Monday night at the Mercury Lounge, Morén, touring in support of his recent solo release The Last Tycoon, proved that he too is most admirable when he embraces control, effectively eschewing pomp and contrived clutter in favor of indelible melodies and wit. Seizing the stage, the opening song (“This is What I Came For”), and consequently the audience, Morén began the night engaging, rhapsodic, and composed. The song beats bow out to hand claps eventually, like so many of his tunes, while the tune itself relies on the intricately beautiful guitar line and choric verses. By the time the chorus arrives, it’s affable and hummable, its lyrics depicting the narrator’s attempts to intervene into an affluent individual’s struggle with pedigree and integration. Morén’s personality, awkwardly open, inserted itself when he sang “your heritage is cute not brave” and “you’re a spoiled white kid with clenched white teeth.” The song epitomizes Morén’s balance between melody and harmony, guitar and accompaniment, and verse and chorus, and established a fine precedent for the rest of the night. But as quickly as Morén showed off his flair for taking unconventional melodies and rephrasing them into ostensibly simple, beautifully lingering songs, he lost it. Overwhelmed by the task of overcompensating for his deficient backup (opener Tobias Froberg on bass, keys, and occasionally drums) and professing jetlag from an overnight flight from Ireland, Morén was visibly flustered, going so far as to confess that his “mind is not but my heart is here.” Credit Moren with being ambitious enough to sing the bridge of “Tell Me in Time” a cappella sans amplification (not an impossible task at the divey Merc Lounge). But the self-described “jazzy” song either eluded him at this point or the line was too dissonant to convey any concrete melody. Consuming the majority of stage left was the setting for the impending string trio on “Le Petit Coeur”, an impressive addition for such an intimate and roughly hewn concert. The players seemed more excited than any of Morén’s professional backers — even more so when Morén invited them to stay and clap backup on “Social Competence”. Since his tenor is ill suited to the baritone opening of “Coeur”, Morén reasonably sang the second verse an octave higher like the rest. Unfortunately, the transition left a sour taste: the juxtaposition with his normal range left a sonically jagged edge, totally disrupting the otherwise sonorous sounds. He should have restrained himself and stuck to singing in his range. As the album’s marketed single, “Social Competence” was anticipated, expected, and followed the script for appeasing the crowd’s demands. But like other songs, its performance was more likeable because of its accompanying story. It turns out that the song is a direct portrayal of the vacuous banter of a teacher’s lounge and the “calculated boredom” Morén once was subject to. Though the chorus loses the song’s initial charm, its desperate relief paints a funny picture: condescending, pretentious post-punk rocker getting cornered by belligerent chatter about the weather and lunch. Naturally, Morén wasn’t about to disassociate from his regular backers, Bjorn and John, and their surprisingly successful Writer’s Block. Declaring at one point that the trio was the archetypal rock outfit, it was no surprise he employed Froberg and a drummer for many of his selections. It also explains the cloud of awkwardness that would descend each time he embarked on a Bjorn and John-less tune. The appeal of “Objects of My Affection” is the anxiety and excitement of a rejuvenated heart, as mimicked by the pulsating snare drum. Without it, the tune can still remain a likeable and earnest ballad, but sloppy drumming impeded any of the song’s underlying emotion. With Froberg playing the glockenspiel melody to “Paris 2004” — on what looked like a toy, no less — Morén tried to recapture the intimate snapshot created by this postcard of a song: café breakfasts with croissants, lazy strolls down the boulevards. Whereas John originally played the melody and also carried the beat, Froberg, misleadingly seated at the drums, played only the single part. His glockenspiel playing was as distracting as the absent drumming. Even Morén’s gentle shuffles and sways away from the microphone seemed off-balance from the encumbering accompaniment. What started as a balanced and restrained evening soon sounded uncomfortably casual before turning into karaoke night. Morén ripped through invigorating covers, but the slipshod accompaniment accelerated alongside. Honoring fellow Scandinavians a-ha, Morén commanded a thrilling “Take on Me”, himself covering both rhythm and lead guitars (at times almost simultaneously) while the crowd eagerly sang along with the chorus. It was during the extended outro that Morén’s energy seemed to finally erupt, sending him into a gleeful frenzy regardless of what time-zone his head, or heart, was in. Though most of his set was (and chord changes were) dictated on the spot to his backing mates, Morén’s impromptu finale, “Me and Julio Down by the Schoolyard”, came as a delight. Like Paul Simon, his nasally voice easily perforates any backup and, as we all learned from the ubiquitous “Young Folks”, the man can whistle, too. The disjointed nature of the evening prevailed, however, and instead, Morén’s spirited cover developed a dangerous inertia from which his straggling friends had to be pulled to safety. Opener Tobias Froberg — looking the part of a grizzled sailor — may have detracted in his backing efforts, but he did contribute a valuable few moments to the evening by performing “You Are Someone I can Believe In” along to a Billie Jean drum sample. Meanwhile, Morén’s balanced playing was, though frequently muddled by coarse contributors and a jet-lagged head, just as indulging when it came off well.