Mark 14:51 And there followed him a certain young man, having a linen cloth cast about his naked body; and the young men laid hold on him: 52 And he left the linen cloth, and fled from them naked.
On the basis that only Mark records it and that John Mark’s mother had a house in Jerusalem:
Acts 12:12 And when he had considered the thing, he came to the house of Mary the mother of John, whose surname was Mark; where many were gathered together praying.
I am inclined to believe that the young man was John Mark himself, who wrote the gospel of Mark.
But I cannot prove it.
I hope you find this helpful.