Praise be to Jesus and Mary, now and forever. 
Today's Gospel is taken from John chapter 13. We're at the Last Supper. We hear our Lord say to the Apostles, "Amen, Amen, I say to you, one of you will betray me," John 13:21. St. John prefaces Jesus' words by saying that he was deeply troubled when he shared that. I'm sure the disciples would have been equally deeply troubled at the same time.
Apart from the beloved disciple, two other disciples are brought to the forefront in this passage. They are Judas and Peter. Both of them are flawed men. Judas is identified as the betrayer, so we can call him the unfaithfully flawed disciple. Peter, on the other hand, is the faithfully flawed follower of Christ. Let's just take a look at them each briefly.
First of all, Judas. At the Last Supper, our Lord told St. John that the one who would betray him is the one whom he hands the morsel of food to after having dipped it, and then he handed it directly to Judas, John 13:26. These words were shared by our Lord presumably only to St. John, and in a low voice, sotto voce, as they would say in Latin, because St. John tells us that everyone else thought that Judas left afterwards because he was going to run an errand or do something of that sort. We read that in verses 28 and 29. So no one realized he was going out to betray our Lord.
St. John Chrysostom in his commentary says that it's most likely the case that the words of Jesus about the betrayer were heard only by John. And if we think about it, I think that kind of makes sense too. If the other disciples would have realized that Judas was leaving in order to betray Jesus, do you think they would have actually let him out of the room alive? I seriously doubt it. They probably would have killed him actually on the spot, which was not part of God's plan. So the identity of the betrayer remains concealed until a little while later when Judas kisses our Lord in the Garden of Gethsemane, and there a bloody fight breaks out to the point that you stop and think, and you say, well, yeah, they probably would have killed Judas in the upper room if they would have known his plans.
After Jesus handed Judas the morsel, St. John tells us that Satan entered into him, and then Jesus commands him, saying, "What you are going to do, do quickly," John 13:27. I suspect that command was given as much to Satan as it was to Judas. St. Cyril of Alexandria was of the same opinion, that Jesus' words were to the devil himself. Commentator Theodore of Mopsuestia in the 5th century says that by entering him, Satan confirmed the will of Judas, the will to irreparably turn his back on God. Judas is the unfaithfully flawed disciple because he desires his will to be done, not God's will.
And the Gospel passage shifts to Peter, whom we could call the faithfully flawed disciple. We say that he's faithfully flawed because when all is said and done, Peter is faithful, but he's clearly flawed too. In this instance, he promises our Lord that he's ready to follow him wherever he goes. He adds, "I will lay down my life for you," John 13:37. Jesus knows what's coming, so he responds, "No." He says, "The cock will not crow before you deny me three times," John 13:38.
So Judas's heart was set on betraying our Lord. Peter's heart was set on following him. Satan firmly took hold of Judas's heart at the Last Supper. The Holy Spirit firmly took hold of Peter's heart at Pentecost. Before that, he was flawed to the point of denying and abandoning our Lord, essentially because of fear and weakness. With Judas, on the other hand, it's hard to deny that he abandoned Jesus more out of avarice and malice than out of weakness. This is why sins of malice, sins of evil intent, are more grievous than sins of weakness. I pray that the Lord would deliver us from them both. Actually, the malice is actually worse. In his heart, Peter truly had a love for God, but in there was also a mixture of pride, of fear, of human respect, of sin. He had a very human and imperfect heart, but it was reformable. Peter was willing to allow the Lord to mold and fashion his mind, and his heart, and his life. But even after Pentecost, he would still make mistakes at times.
Often the lives of the saints give us the greatest hits of all the wonderful things that they did and said, but the saints had their flaws and their struggles too. Sometimes we're presented with a picture of them that seems less than human because at times it's not a very human or complete picture of them. That's just not my complaint or observation. St. Therese had the same complaint and observation as well, so I'm in good company by saying that.
We can think of Judas and Peter as two types. Judas is the recognize and resist type. Peter is the recognize and repent type. Recognize and resist spirituality focuses on the wrongs of others or the perceived wrongs of others. Recognize and repent spirituality focuses on my shortcomings and failings. Judas focused on the problems that he perceived outside of himself. We see this, for example, in his chastisement of Mary, Lazarus's sister in John chapter 12, when he chastised her for quote-unquote having wasted costly ointment on our Lord. Judas is the finger pointer who lacks self-knowledge and lacks humility, and who ultimately is just not on board with God's plans. Instead of recognize and resist, focusing on the errors or sins or perceived errors and sins of others, Peter's spirit was recognize and repent. He was constantly aware of his own sinfulness, and he was always repentant of it. We think back to the miraculous catch of fish and Peter's response to that, "Depart from me, Lord, for I am a sinful man," Luke 5:8. And then after he had denied knowing Jesus, the cock crew, and St. Luke tells us that Peter went out and wept bitterly, Luke 22:62. He wept tears of repentance.
Recognize and repent is an essential characteristic of Jesus' true followers. Yes, St. Peter, as the leader of the church, corrected and admonished those as was fitting and necessary to his calling, but he first embraced the grace to take the log out of his own eye, to use Jesus' words from the parable in Matthew 7:5. Peter was very much like Moses and King David in the Old Testament, flawed but faithful, a man after God's own heart but always a work in progress at the same time.
For those of us who are close to our Lord but still find ourselves struggling, we should take heart in the example of Peter and we should continually ask Our Lady for the grace to embrace that recognize and repent spirituality. Only then will we be in a position to help take the splinters and maybe even the logs out of our brother's eyes as the Savior counsels us to do in Matthew 7:5. 
Praise be to Jesus and Mary, now and forever.