So I was thinking about returns. The return of a long lost hero... The return of a villain. (Without giving anything away I loved the last two Bond films for the way they show the past affecting the future. Skyfall I think is the best Bond ever with Spectre being a very worthy and great follow up). Returns have to be handled with care.
When I first read TLOTR I had the impression Aragorn/Strider was hiding something (he was, a pretty big secret at that, who he really was!) and that there was something special about him. Yet until I got to the relevant bit in the story I did not know or guess at just what was special. And that I think is the text book way to handle returns. Send out hints this character is special, maybe one or two clues so readers can have fun working out what is the special aspect, but don't reveal the truth until it is the right moment in the story to do so.