Skulduggery takes Xion in with a single glance, one which doesn't tell him much he didn't already know. The mugger shot Xion in the arm, it seems, and while the extensive protection on the part of Xion's friends would normally indicate to Skulduggery that something else had gone very wrong, he chooses to take this particular scene with a grain of salt. Xion is much younger than he was assuming. The protection is no doubt instinctive - on Aqua's part, at the very least.

Doubly so if Xion hasn't gotten her soul gem back yet.

Skulduggery doesn't sit down anywhere, but he does take off his hat and leave it on a table by the door. "Hello," he starts, deciding it's probably best to begin gently. Somewhat gently. "I'm sorry we're not meeting under better circumstances."