This drawing of the Last Supper is interesting and in particular because of the way the unknown artist portrays Judas. Obviously, he's the only one in the dinning room with no halo but look at his body posture. Everyone else is following Jesus with rapt attention. They are leaning towards Him with hands either clasped in prayer or outstretched in supplication but Judas sits stiffly with his elbow on the table and his knees crossed in a studied imitation of casualness. One hand is directed away from the Lord and the other is clinching his precious blood money. He is in the room with the Lord and the others but inside he's already gone. This drawing deftly illustrates the hardened, smug sinner who does not even acknowledge to himself that he is a sinner, at Mass.
Some such as St. Augustine and St. John Chrysostom say that Judas took Communion and was the first to eat and drink condemnation for this profanity. Others speculate that Judas left before Our Lord instituted the Holy Eucharist or defer to Blessed Anne Catherine Emmerich who said that the bread fell from Judas's hand before he could consume it. Either way is a rather sobering lesson and a warning about the deadly seriousness about receiving Our Lord's precious blood and body while in a state of mortal sin.