Speculations are rife that Citadel's Archmaster Marywn will travel to Meereen to tell Daenerys Targaryen about the Others. He may also disclose the secret behind the Wall to her.
Sam Tarly disclosed the secret of the Others to Marywn in the book "A Feast For Crows." Marywn was so moved by the disclosure that he decided to go to Meereen to tell Daenerys about it. Hence, he is expected to disclose the secret to her in the upcoming book "Winds of Winter," according to iDigital Times.
Numerous questions arise as to why Marywn is going himself to Meereen to talk about the Others to the Mother of the Dragons. He could easily send a messenger or even Tarly for the task but he does not do so.
The reason behind Marywn's journey to Meereen could be that he wants to explain the significance of the Others to Targaryen, which only he can do best. Also, as a master of magic he can also explain to her what it means in the context of magic.
Marwyn also possesses an age-old glass candle, which belongs to the Valyrian era. It did not work for numerous centuries but since the sighting of the Others, it has started working again. Thus, it implies that some dormant magical powers are waking up again.
Alternatively, there is another theory that Marwyn may be going to Meereen to tell Targaryen about why the dragons were made extinct. The magic maesters were responsible for their demise and being a maester himself, Marwyn is the best person to explain the reason to Targaryen.
Meanwhile, the author George R. R. Martin disclosed in an interview with Galaxy Edge that the readers must be prepared for more deaths in the upcoming books "Winds of Winter" and "A Dream of Spring." He said that he uses death as a tool to advance the story in his books.
Martin also added that he loves all his characters dearly and does not want to kill them. However, he has to bump them off as the whole series is about wars and voilence.
Watch the video to learn about more spoilers of the upcoming book "Winds of Winter" here: