Liam is a sixth grade student at P.S. 38. He looks very similar to Chad.
He wanted to nickname Mr. Galvin, a science teacher, "Sominex", as a reference to how his science class is boring enough to put students to sleep right away. However, Nate Wright, the unofficial "P.S. 38 nickname czar", turned his idea down because he thought the name was too "tame" and not inventive enough. This was most likely because Nate felt the urge to reject potential nickname competitors.
Behind the scenes
Liam, Derek, Chad, and Chad Applewhite are all drawn similarly. Their physical appearance (size, hair, head) are all highly similar.