A 9-year-old fan of Doctor Who was feeling a bit anxious about Peter Capaldi's long-advertised regeneration in the recently aired Christmas special, Twice Upon a Time. So, Capaldi took the time to reassure him with a handwritten letter. The boy's father, Irish author Brian McGilloway, posted a photo of the letter to Twitter, reading:

Dear David, I hope you are having a very merry Xmas. Xmas is always good fun. Well not always. Not every single second. Regenerating is not completely good fun. And it usually happens about Xmas-time. But you know what? Even though it can be a little bit icky (like really bad flu), it has always, always turned out good for Dr. Who. The new Doctor always becomes your favourite and the one that goes… Well, he never really hoes, he is always there, somewhere in time and space, and if you think about him hard enough you'll see him, and we'll see you. It's like the Doctor says, "Everything ends and it's always sad, but everything begins again, and that's always happy. Be happy." So, have a brilliant Xmas, a happy New Year and a wonderful life – I'm sure you will. All the best,

Peter Capaldi

Doctor ?

#PeterCapaldi is my 9 year old son's fav #DoctorWho and he was dreading his regeneration. And then he got this letter with some words of comfort from the Doctor himself among his Santa presents. Such a kind man. pic.twitter.com/Dki37Wt6Er — Brian McGilloway (@BrianMcGilloway) December 27, 2017

Apparently, sending touching letters to fans is a favorite hobby of Capaldi's. Once McGilloway posted his story, artist and Doctor Who fan Catherine Smith also shared a photo of a letter Capaldi sent to her for her birthday in response to a fan letter she wrote when he was first cast as the Doctor.

When he was cast 4 the part, my kids wanted to send him a good luck letter. I wrote too & mentioned that 23/11/13 was my birthday as well as him having inspired me as an artist . Anyway, when the day came I received this birthday card. Absolutely floored me. My doctor ❤️ pic.twitter.com/5lKUHaywV9 — Catherine Smith 🏴󠁧󠁢󠁳󠁣󠁴󠁿🇬🇧🇪🇺 (@CatherineHSmith) December 27, 2017

It's sad to see Peter Capaldi go, even though we're excited to see Jodie Whittaker as the new Doctor. On the bright side, though, now Capaldi will have even more time for correspondence, so start writing your fan letters today!