"I need lichen for my science project," you say. "A scientist in the making?" he says. "I'll help you down when you're done. I'm only out for a stroll, there's no rush." The lichen is attached firm, but you manage to pry it free with some effort. He offers an arm and helps you climb down. "I'm Avery," he says. "I bet you're thirsty after that. Would you like to get a drink? I know this cute little place."