Romcom isn't a branch of comedy often encountered on the fringe, but that's what double act Lazy Susan are up to – and their show is none the worse for that. Last year, Celeste Dring and Freya Parker were here as two-thirds of the sketch group Lebensmüde, performing as the will-they-won't-they Geordie couple Viv and Steve. She's shy and under her mum's thumb; he's a reformed criminal who dotes on her. Those sketches are reproduced almost wholesale here, and form the backbone to an endearing show, Extreme Humans, that has secured the duo their Edinburgh comedy award-nomination as best newcomers.
Their finest material walks the line, like The Office's Tim and Dawn, between tenderness and ridiculousness. Several of the Viv-and-Steve scenes would scarcely be funny if it weren't for the fact that Parker, who plays Steve in denims and a heavy-metal wig, is a natural clown. In the flashback scene where his dad dies in his arms, the joke – Steve repeatedly pre-empting his father's story – is less potent than the poignancy. Another recurring scene pairs American prepubescent Todd with miserablist blogger Jennifer ("I'd hate my mom, if I had the ability to feel"), and we're soon longing for them to kiss rather than make us laugh.
Elsewhere, the show is more straightforwardly comedic: a woman married to a drawing of a horse; a disposable hand-puppet sequence about a bride with cold feet. There are flashes of pop-culture satire, such as the brown-nosing Oprah-ish interview with a sexist rapper, and a skit skewering sentimental disaster-appeals on social media. But the twosome – both strong actors – are best when revealing the turbulent emotional lives of the nondescript: an office worker pouring forth unrequited passions to her diary; or proud, supportive Steve coaxing introverted Viv to sing karaoke. It makes you laugh, but not as much as it makes you go "aw!".
• Until 25 August. Box office: 0131-556 6550. Venue: Pleasance Courtyard
