Just to clarify something here, an error I might have suggested.
The arrest in the Garden was of Jesus only – not His followers – and the description of events in all four gospels is nowhere near as chaotic as @badger
and I have implied.
Jesus is with his disciples in the Garden when Judas appears, with the soldiers and servants of the chief priest. Judas identifies Jesus with a kiss, and the guard move forward to arrest him. There is a spoken exchange
. Someone (John says Peter) drew a sword and struck Malchus (according to John), the servant of the Chief Priest, wounding his ear, but peace is rapidly restored, before events escalate. There is further discussion
. Jesus points out He was preaching in the temple, and no-one lifted a finger, so why now? (Interesting: no comment about the fracas throwing out the moneylenders, etc. Anyway ...)
Then the guards led Jesus away. All in all, quite peaceable, apart from the brief scuffle and the wounding of one of the servants. If there had been more to it than that, the guard would have gone to work, there would have been a melée, heads bashed, blood spilled. But there wasn't. It's quite possible a number of people had by this time followed the guards, servants, etc., to see what was going to happen. The last thing anyone wanted was a riot, so Peter's assault was played down. He wasn't arrested. It's one of those 'nothing to see here, move along' moments.
Then his disciples leaving him, 'all fled away' after Jesus is led off
. They were not chased, so there's no implication of panic or chaos.
Now here it gets interesting:
Jesus is arrested, and led away. Then:
"And they (the disciples) all forsook him, and fled. And there followed him a certain young man, having a linen cloth cast about his
; and the young men laid hold on him" (Mark 14:50-52).
So it seems to me the text is saying that a young man, clothed only in a sleeping robe, followed the crowd as they left Gethsemane en route to Annas (being closest), and then Caiphas (if we follow the detail in John). Somewhere along the way, the young man is spotted, and other 'young men' try to grab him. I would suggest the guard were busy escorting Jesus, their business was done, so it was probably not the guard who tried to grab him, they had no reason to, but some of the followers. He loses his shirt, and gets away.
Why did they try and grab him? What were they going to do? Who can say – he's not 'wanted', as such, and he's done nothing wrong.
Meanwhile, according to Mark "Peter followed him (Jesus) from afar off, even into the court of the high priest; and he sat with the servants at the fire, and warmed himself." And John has "... Simon Peter followed Jesus, and so did another disciple" (John 18:15) – so although the disciples 'fled', Peter, at least, stayed around, followed to see where Jesus was being taken ... might well have seen the young man, but had no idea who he was, or what happened, or why.