Learn English – Words or phrases that describe a person who is blind to the consequences of their actions

Characters such as Léon are anti-heroes:

a central character in a story, film, or drama who lacks conventional heroic attributes:
with the age of the anti-hero, baddies and goodies became less distinguishable from one another

TVTropes' entry for antihero reads:

An Archetypal Character who is almost as common in modern fiction as the Ideal Hero, an antihero is a protagonist who has the opposite of most of the traditional attributes of a hero. (S)he may be bewildered, ineffectual, deluded, or merely apathetic. More often an antihero is just an amoral misfit. While heroes are typically conventional, anti-heroes, depending on the circumstances, may be preconventional (in a "good" society), postconventional (if the government is "evil") or even unconventional. Not to be confused with Big Bad, who is the opponent of Heroes (or Anti-Heroes, in that matter).

A related term often used synonymously is Byronic hero (Wikipedia):

The Byronic Hero is a type of character (an Anti-Hero, an Anti-Villain, or Just a Villain) popularized by the works of Lord Byron, whose protagonists often embodied this archetype, though they existed before him*. Byronic Heroes are charismatic characters with strong passions and ideals, but who are nonetheless deeply flawed individuals who may act in ways which are socially reprehensible, and whose internal conflicts are heavily romanticized.

Léon is one of the characters mentioned on Wikipedia's list of fictional antiheroes.

The crooked DEA agent would perhaps then be an anti-villain. Both of them are flawed characters (just like Lance Armstrong).

I would call that "sensory overload"

From Dictionary.com:

Part of Speech: n
Definition: "a condition of receiving too much information or stimulation via visual or audio sources; overstimulation of one or more senses"
Example: In sensory overload, it becomes difficult to focus on the task at hand.
Etymology: 1959