So, my monster just brought me his alphabet book to look at, along with his now-common "Book. Read" demand.
So I was going through the letters with him and he got bored and closed it. Then he pointed to the letters on the front and told me "letters". Not terribly uncommon, he loves letters.
There's A B & C on the front, so I told him the sounds each makes. He stared for a minute, then pointed at the C and told me "Cookie". This kid. He did this once before with a V when we were out walking; when I told him the sound, he said his made up word for record player (which starts with V). I thought it was just a freak thing, but it looks like he actually understands the relationship between (some) letters and the sound they make.
What the what? He'll be 18 months in a week.