Hi,
What is the correct use (I think you mean 'form' or 'structure', or 'way to write') for this sentence?
I saw another person and told him I did not think I had ever met a more interesting person. OK
I saw another person and said to him 'I did not think I had ever met a more interesting person.' There's nothing grammatically wrong with this sentence. However, if it is intended to be the direct speech relating to #1 above, the direct tenses are wrong. It should be
I saw another person and said to him 'I do not think I have ever met a more interesting person.'
Best wishes, Clive