Ethan
Ethan is a Temporal Manipulation trainer. Initially he can be found in the South Gate Station cafeteria, after the blockade is lifted he's in Hanging Rat or Hardcore City Bar.
Player interactions
You can further dig his story through conversations in different bar, eventually discover that he use a medallion, made by his psi teacher, Avllin Kain, to cover his old age. Ethan kill Kain to get back the medallion, failing to learn his final lesson.
Psionic trainer
Ethan can train Temporal Manipulation psi skills. In SGS, he can train woman character in two option places, one of which is in protagonist's private room.
He can teach Temporal Distortion, Psycho-temporal Dilation and Limited Temporal Increment if you have the required thought control skill level(and enough credits).