The reply to your question about Arjuna's relationship with Krsna, is that Arjuna is an eternal devotee, so on the higher platform the devotee is so intimately related that he forgets Krsna is the Supreme Personality of Godhead. But, in the lower stage of devotional service Krsna is looked upon with awe and veneration. When Arjuna saw the virata murti of Krsna, actually he came down one step below his position. Therefore he asked for forgiveness from Krsna.
Letter to Acyutananda Maharaja, 1 November, 1973