Harry Potter and Severus Snape's private lessons

After Christmas in the 1995–1996 school year, Severus Snape taught Harry Potter the skill of Occlumency, under the insistence of Albus Dumbledore. As Harry's mind was open for attack by Lord Voldemort, this class was given to Harry for protection.

Lessons were given once a week, under the guise of Remedial Potions. This was to prevent other people from finding out about Harry and Voldemort's connection in the minds (or as the Ministry puts it at that time, Harry seeing things), least by of all Dolores Umbridge, much to Harry's discomfort.

Under Snape's tutelage, Harry repeatedly had his mind attacked in order to train him. Snape also ordered Harry to empty his mind every night as practice. Unfortunately, due to the mutual animosity between the teacher and student, Snape was unkind in his methods, while Harry did not take Snape's lessons too seriously, and neglected to practice. Coupled with Harry being emotionally open at all times, the lessons did not progress much.

The lessons were ultimately cancelled when Harry saw a memory of his father hanging Snape in the air by his ankles and was caught by the Potions master. Snape was so furious at Harry that he threw the boy out of his office and forbade him from ever returning. Despite Sirius Black and Remus Lupin's insistence for Harry to continue, it was never followed through. Harry was ultimately left open for Voldemort's deceptions.

As Harry's was an emotional wizard, he was never able to get the hang of Occlumency but could cancel out Voldemort if he felt grief (or love, as Dumbledore puts it), like about Sirius's death or Hermione being tortured.

Appearances

 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince