“And began to salute him, Hail, King of the Jews!”
Mark 15:18 — Greek Interlinear
Church Fathers on Mark 15:18
The vainglory of soldiers, ever rejoicing in disorder and in insult, here displayed what properly belonged to them.
For since He had been called King of the Jews, and the scribes and priests had objected to Him as a crime that He usurped rule over the Jewish people, they in derision strip Him of His former garments, and put on Him a purple robe, which ancient kings used to wear.
But we must understand that the words of Matthew, they 'put of Him a scarlet robe,' Mark expresses by 'clothed Him in purple'; for that scarlet robe was used by them in derision for the royal purple, and there is a sort of red purple, very like scarlet. It may also be that Mark mentions some purple which the robe had about it, though it was of a scarlet colour.