We can learn a lot about the progression of our sanctification from the way that the Lord called and formed his disciples into the men that he wanted them to be. Each of us grow differently as we draw closer to the Lord in word, thought, and deed. The Lord knows what we are in need of as well as what will need to be mortified and vivified in order to make us the men and the women that he is calling us to be. This is seen very clearly in the different ways that John and Peter grew in grace and knowledge of Jesus Christ.
The faults of the two brethren being so opposite, growth in grace would naturally assume two opposite forms in their respective experiences. In Peter it would take the form of concentration; in John, of expansion. Peter would become less charitable; John would become more charitable. Peter would advance from indiscriminate goodwill to a moral decidedness which should distinguish between friends and foes, the Church and the world; John's progress, on the other hand, would consist in ceasing to be a bigot and in becoming imbued with the genial, humane, sympathetic spirit of his Lord. Peter, in his mature state, would care much less for the opinions and feelings of men than he did at the present time; John again would care much more.
~A.B.Bruce, The Training of the Twelve, p474