Roose Bolton is known as the "Leech Lord" in the books because he's really obsessed with leeches! Arya Stark on multiple occasions in "A Clash of Kings" has to clean up leeches while serving him at Harrenhal and he's known to have pale skin due to the regular leechings.
When Roose Bolton takes over at Harrenhal he has Arya Stark as his cupbearer in "A Clash of Kings." (She never serves Tywin Lannister like she does in the show, but she's there at the same time as him doing other work.) Roose asks Arya how she feels about leeches, to which she indicates she doesn't care. After that we see Roose Bolton getting leeched, often. He believes it gets rid of the bad blood and on one occasion in "A Clash of Kings" has a meeting with Freys where he is leeched while naked. The visual... it's not pretty.