Janius did not stop Colours from leaving. He didn't even acknowledge him. Colours had taken the hint.

At this point, Janius was almost losing his patience with Kaleeth. The claims she was making were ridiculous. "I've lost friends to skooma, Kaleeth. Do you think I wouldn't try everything in my power to keep you away from it, even if it was patronising?!" Janius hissed through his teeth and gestured randomly, frustrated, "Colours made it sound like so much fun, the way he talks of it so casually!"

This was the first time Janius had raised his voice in a long while. It was not in his nature to get as riled up as this, unlike Fendros. Although, it probably wouldn't do well in placating Kaleeth.