Ender

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Der Grobmann

Made me chuckle a bit If you don't have a "ß" on your Keyboard, you should use "ss" instead. (ß is pronounced like a sharp s) "Großmann" means "Tall man" , "Grobmann" would mean something like "thug" or "ruffian".
Made me think of a Slenderman with prison tattoos wielding a huge club xD

Anyway, back to the story.

Spoiler below!

I think whats lacking a bit still (or maybe you just didn't mention it to keep things short) is the clear motivation of Baron Redwood. If there was a reason for his behaviour other than "he just does what slenderman tells him to do", it would make the story more interesting and also provide you with several possibilities for the ending. For example you could reveal a motivation that puts his actions in a different light and suddenly makes us think differently of a character we previously thought to be evil.

Also, but this is more my personal taste, I would prefer the connection between Alexanders family (really, change the name, its a bit confusing because one always thinks of characters named Alexander as being the evil ones) and the Baron to be less "forced" plot-wise.
Its a bit weird that he would come to the Baron for protection - if he doesn't even believe Slenderman is a real danger, why would he do that? You could solve that more elegantly by just having him be a servant of the Baron that lives on the castle grounds with his family (not too unusual for a castle to have "servant quarters") or something like that.