A.T. Robertson Commentary Mark 14:51

"And a certain young man followed with him, having a linen cloth cast about him, over [his] naked [body]: and they lay hold on him;" — Mark 14:51 (ASV)

A certain young man (νεανισκος τις). This incident alone in Mark. It is usually supposed that Mark himself, son of Mary (Acts 12:12) in whose house they probably had observed the passover meal, had followed Jesus and the apostles to the Garden. It is a lifelike touch quite in keeping with such a situation. Here after the arrest he was following with Jesus (συνηκολουθε αυτω, imperfect tense). Note the vivid dramatic present κρατουσιν (they seize him).