"You'll need a bigger cape, Steve. A great hero needs the best cape he can get," she informs him sagely. "How else are people going to know about your deeds?"

Okay, she might be mixing up traditions a bit there, but he won't know.

"More or less. The first Titans raised the wall around the City when it was still little more than a refugee camp. Guarding it has been the first duty of our orders ever since. Once you step beyond the Wall, you're in hostile territory. We seek out any survivors we can and guide them home, but Earth's a big place. And there aren't too many of us these days."