Alastor crossed his arms, the two inches or so difference in their heights doing nothing to diminish the air of intimidation he was going for. He had to give the young man credit for pluck. It could get him killed, but he got some credit for loyalty to his friend.
Eyeing Vaisey curiously, Alastor weighed his options. If he let the boy go with orders to return to Headquarters, he could just slip back in through another entrance. Alastor was very familiar with Potters and the loyalty they inspired in their friends. He could keep the boy here in this quadrant and make sure he was useful and far away from the action he wasn't supposed to take part in. Reprimands could be left to Potter, later.
"You do realise I'm well within my rights to make your life a living hell for disobeying a direct order, Vaisey?" Sending a cushioning charm under a child about to fall over the rail behind them, he continued to stare "down" Vaisey with his good eye.