u/Aware_Ranger_4144

So she visited sherlock as faith. Did they actually hang out? Or was she just made up by sherlock's mind? If she did visit, then why in the survalliance cameras sherlock was alone Or when sherlock told mrs Hudson she is going to hang out with a friend, Hudson asked "what friend" and also during the time when sherlock and faith(eurus) were having chips, she suddenly disappeared?

Or if she didnt visit sherlock, how did sherlock knew about the letter? I know the letter/paper (where its written someone is going to get killed, but who) ended up at sherlock's house and sherlock found it, but before that, sherlock technically saw the letter

I would appreciate any enlightenment