The SCP Foundation is purely fictional. It's a collection of imaginative and often creepy stories and characters that are made up for entertainment purposes and have no basis in reality.
SCP 106's origin is rather mysterious. It is an extremely dangerous and malevolent entity within the SCP Foundation's lore. Some believe it has existed for a long time, perhaps emerging from some sort of dark dimension or abnormal space.
No. SCP 939 itself is part of a very dark and often disturbing SCP Foundation concept. And when you add 'lemon' which usually implies sexual or inappropriate content in fanfiction, it is definitely not appropriate. It goes against the standards of decency and morality.
SCP science fiction is about a fictional collaborative writing project. It contains a lot of 'creations' known as SCPs. These SCPs can range from living creatures with abnormal powers to inanimate objects with mind - boggling properties. It has a large online following but also has faced criticism for its often dark and disturbing content.