“You sing along at home. There’s no reason why you shouldn’t do it here, all right?” said a slightly marble-mouthed Jeff Mangum Friday night as he introduced “Holland, 1945,” one of the most fondly remembered eccentricities of his cult band, Neutral Milk Hotel. But it took the crowd at the Lincoln Theatre a few moments to warm up its own vocals; who’d want to outsing a guy whom, you could have once fairly assumed, would never appear onstage again?

Eventually, the crowd participation grew from a hesitant hum to full-blast accompaniment, and the most remarkable thing about the evening—-Mangum’s first of two shows in D.C.—-was how he used his fans’ goodwill as an instrument in its own right. At several points, he lead them in la-la re-creations of horn parts. In “The King of Carrot Flowers Pts. Two & Three,” Mangum sang, “Jesus Christ, I love you, yes I do,” and the audience knew to hold the last word of the lyric as Mangum proceeded to the next line: “And on the lazy days, the dogs dissolve and drain away…” He pulled a similar trick midway through “Oh Comely.”

Mangum was right: They do all sing along at home. Mangum disbanded Neutral Milk Hotel in 1998 and has performed only very occasionally since, so most of his fans had only heard his songs one way (or maybe two) before the past six months’ acoustic gigs: on the studio albums. In his absence, Mangum became one of indie rock’s favorite recluses, and Friday’s gig was a testament to his fan’s intimacy with the material and their empathy for the man.

Which, you know, still didn’t rule out heckling. “Don’t disappear for so long next time!” shouted one fan to nervous chuckles. “What did you want me to do?” Mangum shot back, and the crowd roared. He smiled. “I deserve a little shit. I was gone for 10 years.” In other words: He had every right to disappear for as long as he did. But he was grateful to be back.

Sometimes, you were glad when the singing-along died down: Mangum’s voice is still singularly nasal, evocative, and—-when he stretches out a note—-disarmingly free of vibrato. Other moments were straight-up group hugs. For his encore, Mangum performed “In the Aeroplane Over the Sea” accompanied on musical saw by Julian Koster, of openers The Music Tapes. Much of the previously seated crowd rushed to the front of the theater, but after Mangum retreated with a smile and a wave, they stayed put, clapping for more music, even as the speakers began to play a go-home-now soundtrack. He came back with “Song Against Sex.”

In the end, then, there was no ex-recluse freak show, no weirdness to pay off the 13-year absence’s accumulated mystique. Instead, we got a concert that was, well, pretty gratifyingly normal. Mangum even looked kind of unremarkable, at least to my eyes: newsboy hat; stringy, inky black hair.

Well, maybe. A colleague who was in the audience sent me an email a few minutes after the show ended. “If he wants people to stop worrying about him, he should stop looking and dressing like Elliott Smith circa 2003.”