Why does brick on the tv show the middle whisper after he talks?

The character of Brick on TV's Middle has quite a few quirks, one of which is his repeating of the last thing he says in a kind of creepy whisper. No explanation is given for this, as viewers we're just supposed to accept that this is one of his "tics." Another of Brick's quirks is carrying ketchup packets in his pockets; they "soothe" him. Brick is played by Atticus Shaffer (born 6/19/1998 in Santa Clarita, California), who has played this role since the series debuted on 9/30/2009.

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