Just One Cup

My shop is open every day from 6 am to 10 pm. There's a giant man who comes in, always in the corner with his black hot coffee and classic book. He's there every day from 9 pm to 10 pm. After that, he waits outside, drinking his second cup, until I lock up. I've never really talked to the man, except to take his order. However, he follows me two steps behind until I get home and lock the door. At first, I was a little spooked, so I started carrying a knife and pepper spray. The next day, after I began carrying, he told me, as I took his order, that it was good to carry a weapon, and I should be very careful.