It's the curse that tipped him off. Or rather, the lack of it.

Enjolras had avoided the Cornucopia, trusting that this Arena, like many of the others, would have enough supplies hidden within its layout. It was a gamble, but one that wasn't without it's calculation. Besides which, the Cornucopias were rarely not a bloodbath and if there was one thing working out with Venus had taught him, it was that he wasn't a match for anyone who had any experience in close combat.

Which left him to track down his friends on the outskirts of the conflict. There was no telling which way they would have gone, no way for them to have planned this at all. This could be calculated. This had to rely on luck. It was likely due to the sensory deprivation of the fog that Combeferre's voice stuck out to him, even choked as it is. There's something familiar in the shout, and as he wandered toward it, Enjolras was hopeful that it will be one of his friends, that he would be one step closer to gathering them so that they could begin the Games with a consorted effort.