It has been traditionally assumed that Lord Jesus was alone with His Apostles in the Upper Room during the Last Supper (Luke 22:11-12), because the Gospels only mention Him and the Twelve in dialogue and reference (Matthew 26:20; Mark 14:17; Luke 22:14), and especially because that night, the Sacrament of the Eucharist was instituted, and implications of authority motivate to think this way even more. But reading carefully into the four narratives, there exists the probability that more people apart from the Twelve Apostles may have been present at the time to celebrate the Passover, at least at some point of the night, and without affecting the narrative and its teaching.
SOMEONE ELSE’S HOME
Lord Jesus did not celebrate the Last Supper at home, in the north of Judea, but in Jerusalem, supposedly away from His immediate blood family, St Mary and his brethren, and other second-degree family. He requested a room for hire from someone else, probably dedicated to this business, and who was most probably a believer in the Lord, since they seemed to know each other, and was ready by the time the Apostles went to see him (Mark 14:13-15).
From the narrative of His arrest and Passion, we know Lord Jesus’s family may have been already present in Jerusalem that week. St Mary and the other Marys, including Magdalene, were present the next day during His trial and Crucifixion
(Matthew 27:55-56; Mark 15:40-41; John 19:25).
It is very possible that if not a relative of Lord Jesus, or one of the Seventy disciples, at least the owners of the house were also present at some point during dinner, at least until before the Eucharistic institution. That would explain why Lord Jesus, when He was asked about who would betray Him, after He had already said “One of you” to the whole there present; He later clarified “It is one of the Twelve”, which would be redundant if only the twelve apostles were present.
A quick overlook of the four narratives makes us assume that maybe only Lord Jesus and his Apostles were present, after all, the dialogue only happens between them in the narratives. However even if more people were present who had no play in the message of the evangelists, or that came up only to share the meal as such but not to participate in the eucharistic institution, they may have been left aside by the writers, and the dialogue only concentrated on the protagonists of the main story.
There is no obstacle at all for more people being present at the Last Supper or any theological traditional teaching jeopardized if that was the case. It may have been the believing owner of the home, which it would have been expected, or the mysterious man who ran away naked during the arrests, who does not seem to be part of the Twelve (Mark 14:51-52) but “followed Jesus” from somewhere at early hours of the morning.
Even if more people were present that night, to share in the Lord’s last Passover meal, the place, commission and authority of the Twelve Apostles is unchallenged and irreplaceable as “Apostles of the Lamb” (Revelation 21:14).