Not all of them, just some of them. LIKE. Kelpie is a water horse who eats human flesh (except the liver), for example. Sprites aren't fairies so that's a whole other story, but they're pretty violent. There are also unseelie courts like hellhounds and whatnot that are pretty carnage-loving, but Brownies (little guys who like mischief but are adorable and overall harmless), Banshee (in HtY, not like the common screechy banshee), Clurichaun (they love wine okay)-- they're all pretty chill. There are tons more, obv, but those are some examples that are actually in the series or mentioned in it.

AHAHA they probably won't have to worry about anything besides him getting told off..