Fade to Black

Julius Leichtenberg is a retired German soldier and is now raising a child in his home country. However, upon raising the child, eerie events take place here and there. The more the child grew, the more uncanny would the events around him happen.

Then finally, on an oddly dark Christmas day...

Prompt: All I want is a dark Christmas
Theme(s): Thriller, Dark, Horror
Setting: Late 20th Century

Please note that Julius starts the actual adoption at chapter 7. Everything else before that chapter is just one big prologue.