Say what you will about how Harry Potter increases in complexity and darkness as it progresses but I think JKR sets the tone of the series pretty well when she has Dumbledore play ding-dong-ditch with a baby in the first chapter
They literally starved him in the second book before Ron came to rescue him. I found that pretty horrifying. It went on for days IIRC. And they weren’t feeding him much to begin with, which is why he was so skinny and short.