For the Tell-Tale Heart I would try link the narrator's descent into insanity and his contemplation about life to Prospero's journey. There are slight links there.
As with Invictus are you doing the poem or the movie?
If its the poem you could try link to the ideas of self-discovery or spiritual discovery of again Prospero as he learns to forgive as he realises the power he has... or even the bond between Alonso and his son Ferdinand and the pain and angst the king feels as he loses his son and how helpless he feels. (i.e. the opposite of the poem, this guy gives up).