Unlike a lot of child actors in American shows, the one is this isn't that annoying but then again, he's mute throughout the story! Interesting episode in this series where the main protagonists are still finding their feet and getting into character.
Bit of a hoary plot of the 'ghost from the past returning to wreck revenge,' but handled pretty well and has a few twists and turns to make it extremely watchable.
All of which give the brothers the clues to crack the case.
Due to shock from seeing his father killed by the wraith and can only communicate to the world via his drawings.