Iain had a damn good point there, and hell if Lachlan had been in his right mind he would have realised that before he said it.
If he maintained he was clean Iain would think he was lying. If he admitted to falling off the wagon, he would be lying.
Or he could explain to his brother than his boyfriend happened to be the human embodiment of Codeine. That'd go over great.
"M- maybe I'm jonesing?" he suggested in a small voice. "Are you mad?" Considering what Lachlan had been like when he was using, he couldn't really blame Iain if he was angry. "I won't run away again."