A smirk played on Blaise's lips as Theodore talked, bringing up the concert again. He could see him fitting in with his appearance, but knowing his personality, he knew that he wouldn't last there. Not that he couldn't, just that he wouldn't. Unless someone was using something on him - it made Blaise wonder what he would be like under the potion. It'd really changed some people and others not so much. It was a very interesting potion and an even more interesting idea.
Once his Mark was out in the open and Blaise was completely aware, he grabbed his glass once more. His eyes didn't leave Theodore's as he sipped from the drink, silently urging a Legilimens spell as he tried to enter his mind. It would be one perfect opportunity - the Mark was difficult to miss and hopefully his thoughts would venture on it and related things for at least a moment. It would also be a test, his first toe in the waters. Without breaking eye contact, he lowered the glass back down and licked any excess drops from his lips.