Truthfully, Penelope had been quite surprised when she received Percy's owl, asking her to meet him in Diagon Alley. For a long while, Penny had been staying mostly out of the Wizarding world, feeling as though she was drawing less attention to herself by moving back home and connecting with her Muggle roots until the conflict blew over. Although Percy's letter hadn't been very indicitive of anything at all, Penny knew him well enough to be able to tell that he wasn't just writing to ask how she was - he clearly had a motive in seeing her, and it was Penelope's curiosity, and general alertness when it came to the impending war, that had her acquiesce to the request.
Still, although she had known Percy for years and didn't really have too much anxiety over meeting with him - not beyond the general level of a girl seeing her ex-boyfriend for the first time in half a year - Penny was feeling the same sort of physiological effects as Percy. She was of course nervous to be in Diagon Alley, in broad daylight; she had tried to to convince herself beforehand that she had every right to be there as anyone else with Wizarding blood, but she still knew that the world wasn't very safe for her presently. As she approached the outdoor cafe, though, and spotted Percy's bright hair in the small gaggle, she forced herself to appear and behave more confidently, smiling civily as she reached the table, "Hello, Percy."