After saying these things, Jesus was troubled in his spirit, and testified, “Truly, truly, I say to you, one of you will betray me.” The disciples looked at one another, uncertain of whom he spoke. One of his disciples, whom Jesus loved, was reclining at table at Jesus' side, so Simon Peter motioned to him to ask Jesus[f] of whom he was speaking. So that disciple, leaning back against Jesus, said to him, “Lord, who is it?” (John 13:21-25, ESV)Common translations describe John as lying at Jesus' side. The KJV translates it more accurately as leaning on Jesus' bosom. That better conveys the intimacy of the moment.
I'd love to see a painting of this scene, if only just to see what artistic choices were made in depicting it. (An aside: does anyone familiar with art history know if this moment was ever captured in art form?) If I were a master artist, I'd want to capture the moment when John, upon having their enjoyable fellowship disrupted by the abrupt news of Jesus' betrayal--hence slightly confused, not having fully taken in what was just said, but with a glint of worry beginning to form on his brow, having already immediately sensed a hint of unease and tightness forming in his friend's throat, then clearly hearing a note of trouble or sorrow in his voice--slowly lifts his head from Jesus' chest, where just a second ago it lay comfortably and perfectly still, and starts to turn his head to face Jesus in order to look at him squarely eye to eye, and listen intently, so that he might learn what is so profoundly troubling his friend.
Evidently, it is John who is closest to Jesus--in both senses of the word, that is, in terms of both literal proximity and intimacy of relationship--for the other disciples to rely on him to pop the uncomfortable question "Who is it?" It's at this moment, tender as it is tense, when Jesus reveals the identity of his betrayer. (It's a confusing moment, no doubt. Nobody seems to get that it's Judas, even when Jesus hands him the piece of bread while announcing, rather straightforwardly, in no ambiguous terms, that this act will identify his betrayer.)
Jesus speaks to close friends. He shares things that must be held in the strictest confidence (at least for the time being). It's in this setting, with John's head resting against his chest, that he chooses to say some of his greatest prophetic words immediately preceding his passion, death and resurrection.
A word about timing. This takes places just after the foot washing ceremony Jesus chooses to hold before enjoying a nice passover dinner with his disciples. It is the same scene in which Peter--stupidly--requests a full-body wash, thinking it is extra spiritual and will bring him closer to Jesus. (It's worth noting that John--maybe because, being the favored apostle, he was more secure in Christ's love and didn't feel the need to prove himself?--never feels the need to make--at least he never expresses--such a silly request. Or perhaps it's partly for this very reason that he was Jesus' favorite. Mind you, it's only moments later when Philip hastily places another request--one equally dumb as Peter's but even more obnoxious--that Jesus "Show us the Father.")
Older depictions of physical intimacy in same-sex friendships can already be found in the Old Testament, when David and Jonathan are found kissing and weeping as they say their tearful goodbyes. They are the paradigm ancient example of how two straight men can not only put on (what would be by today's standards count as) embarrassing displays of affection without fear of "sinning" or having their sexual preferences misunderstood. There is nothing untoward in expressing such love. David himself was unafraid to proclaim the wonders of a love "more wonderful than that of women" (2 Samuel 1:26).
The example of Jesus and John, perhaps to a lesser degree, suggests the same lesson: as Christians, we shouldn't be afraid of tangible expressions of affection between friends.