In Shakespeare's Richard III, Clarence and Buckingham both trust Richard, who repays this trust by having them killed. Clarence, who has only a small part at the beginning of the play, is portrayed as an honorable fool, quite out of place in the Plantagenet court, and unaware of the machinations going on around him. He is innocent and trusting in his attitude to Richard, though he is much more intelligent after death, when he appears as a ghost and sides with Henry Tudor against his treacherous brother.
Buckingham is a stronger, more astute, and less honorable character than Clarence. He is morally flexible and is willing to be Richard's partner in crime up to a point. However, he hesitates to participate in infanticide and does not obey Richard's order to murder the princes in the tower. This shows that, unlike Richard's, his villainy has some limits.
Buckingham shows some of the same naivety as Clarence in his assumption that, despite his refusal to kill the princes, Richard will nonetheless reward him for his loyalty upon becoming king. He shows his practicality and capacity for resentment and revenge when he rebels against Richard and allies himself with Henry Tudor, but he never quite has the ruthlessness or recklessness which win Richard his brief success.