Getting close to a Taller is ill-advised, as the creature can easily kill Simon with little effort. The Taller will punch Simon if he gets too close, which will send the player flying and onto the ground where they will be immobilized. The Taller will then approach Simon while he is incapacitated and stomp on him, finishing him off brutally. It is possible to stand up after being hit by either clicking the mouse or pressing the jump key.
Note: Originally you could crouch in front of this enemy and attack the Taller without him attacking back. This was taken out when Patch 1.2 was released and you are now currently unable to do this.
Simons relation: The Taller could possibly represent how Simon feels about people that can walk. Like how they "whack" Simon, and walk and stomp on him. Since Simon is handicapped, He may feel everyone is "taller" than him because of his disabilities.