He went out as was his custom
To the Mount of Olives.
The disciples also followed him.
Having come to a place, he said to them,
Pray that you may not enter into Trial.
He went apart from them
About a stone's throw.
Kneeling down, he prayed, saying,
Father, let not my will be done, but thine;
If thou willst take away this Cup from me.
Having risen from his prayer,
He came to his disciples. * He found them asleep.
He said to them, You sleep!
Rise and pray
That you may not come to Trial.
This is the last request in the prayer Jesus taught them (xi. 4). The cup into which his blood will be poured (22:20). Jesus here sets an example to Christians not to seek Trials, but to pray that they may be spared them. Having neglected this prayer Peter, the first, will fail in the Trial.
(The Creation of Christ, p. 420-421 my bold)
Peter ignored the meaning of the prayer, being otherwise ready to receive persecution in order to prove his allegiance to Christ and his supremacy among the other apostles (etiamsi omnes, ego non) .
A strong indication that Mark didn't like this antithesis (fear of Jesus versus audacity of Peter) is proved by the fact that Mark introduced only a word, Abbà, in the prayer of Jesus:
(Mark 14:35-36)35 Going a little farther, he fell to the ground and prayed that if possible the hour might pass from him. 36 “Abba, Father,” he said, “everything is possible for you. Take this cup from me. Yet not what I will, but what you will.”
In this way, the antithesis ceases to be
'fear of Jesus versus audacity of Peter'
...to become rather (part of) the antithesis:
'innocence of Jesus versus guilty of Barabbas''.
Now Barabbas will be spared the first Trial, differently from Jesus.
In this way the point of Mark is that the persecutions must be sought (as Jesus) and not escaped (as Barabbas).