"That's chess! You've got to make some sacrifices! I take one step forward and she'll take me -- that leaves you free to checkmate the king, Harry!"
-- Ron Weasley
The only way across a large chamber with a chess board for a floor is to play across using massive chess pieces. Ron, the chess expert of the trio, takes the place of a knight and directs the game. He eventually realizes that the only way for Harry and Hermione to progress is to sacrifice himself. He allows the White Queen to smash him with her stone fist and the others reluctantly leave him behind as they go on after Quirrell.
Ron was a knight. Knights certainly embody Gryffindor traits like chivalry and courage.