It wasn't meant to happen. He absolutely positively did not mean to do it. Really.
But now his mouth is on Louis' and the hotel room has gone silent except for the low music playing from someone's ipod and he should be pulling away, not opening his mouth for Louis' tongue and - oh god is that him making that noise?
They pull apart with a slick sound that makes Liam's face burn and he doesn't know where to look, so he keeps his eyes down, accidentally focusing on Louis' collarbone peeking out from under his collar. He kind of wants to bite it.
"Okay," Harry says, sounding bewildered. Liam chances a glance at the boys and they're all staring back at him, frozen. He looks at Louis, who smirks and squeezes his neck, making him drop his head forward just a bit and that seems to break the spell because Harry is crawling towards them - actually crawling on his hands and knees oh god - and sliding his fingers under Liam's chin, tilting his head up so their mouths meet. He almost forgets to react, still stunned by this turn of events, but Harry's tongue flickers across his lips and he opens up automatically, and it's so good, of course it is, Harry's mouth skilled and hot on his.
"Jesus," Zayn breathes, and then he hears rustling clothes and a quiet giggle from their side and he breaks the kiss to have a look. Zayn has Niall pressed back against the couch; hand on his throat tilting his head back as they kiss, the contrast of their skin stark in the low light. Harry moves slightly away from Liam to kiss Louis and Liam can't help but watch that, watch the way their heads tilt together, the strong line of Louis' jaw moving as he kisses Harry hard. Liam doesn't even think about it, a running theme for the evening, and leans in to bite at Louis' jaw, making him moan into Harry's mouth.
He hears more movement, then suddenly Zayn is sitting next to him on the couch and Niall is next to Harry in front of them and Liam is leaning forward, pulled helplessly by Niall's red mouth and mussed up hair. Zayn presses in close, draped over his back and Liam hears him murmur to Harry and Louis, but he's lost in Niall's mouth, Niall's hand clutching at his thigh as he kisses back almost desperately.
They have to stop for a moment, needing to breathe and he realises he hasn't kissed Zayn and that he needs to. He twists around and presses Zayn back against the arm of the couch, and Zayn tilts his head to meet his frantic kiss. Zayn slows him down, runs his fingers through Liam's hair then uses it to hold him still, opens Liam up in a completely new way and kisses him so deeply that Liam thinks he might drown.
They peter off into smaller kisses, soft and closed mouthed until they're just breathing into each other's space and holding on. Zayn smiles at him and looks over his shoulder, and Liam turns to see Harry and Niall kissing with Louis watching them interestedly.
It wasn't meant to happen, but it doesn't mean Liam isn't glad it did.