JC - Chapter 20

On of the more interesting stories if the New Testament is when the Savior crossed the sea of Galilee where -

"...immediately there met him out of the tombs a man with an unclean spirit,
3 Who had his dwelling among the tombs; and no man could bind him, no, not with chains:
4 Because that he had been often bound with fetters and chains, and the chains had been plucked asunder by him, and the fetters broken in pieces: neither could any man tame him.
5 And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones.
6 But when he saw Jesus afar off, he ran and worshipped him,
7 And cried with a loud voice, and said, What have I to do with thee, Jesus, thou Son of the most high God? I adjure thee by God, that thou torment me not.
8 For he said unto him, Come out of the man, thou unclean spirit.
9 And he asked him, What is thy name? And he answered, saying, My name is Legion: for we are many.
10 And he besought him much that he would not send them away out of the country.
11 Now there was there nigh unto the mountains a great herd of swine feeding.
12 And all the devils besought him, saying, Send us into the swine, that we may enter into them.
13 And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand;) and were choked in the sea."  (New Testament | Mark 5:2 - 13)

I don't know if I have ever encountered one as such.  What I found also very interesting is -

"...he that had been possessed with the devil prayed him that he might be with him.
19 Howbeit Jesus suffered him not, but saith unto him, Go home to thy friends, and tell them how great things the Lord hath done for thee, and hath had compassion on thee.
20 And he departed, and began to publish in Decapolis how great things Jesus had done for him: and all men did marvel."  (New Testament | Mark 5:18 - 20)

Of this missionary zeal, Elder Talmage commented -

"The man who had been rid of the demons feared not; in his heart love and gratitude superseded all other feeling; and as Jesus returned to the boat he prayed that he might go also. But Jesus forbade, saying. “Go home to thy friends, and tell them how great things the Lord hath done for thee, and hath had compassion on thee.” The man became a missionary, not alone in his home town but throughout Decapolis, the region of the ten cities; wherever he went he told of the marvelous change Jesus had wrought on him."

It sounds like he remained faithful.