Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

In the episode The Sign of Three (S03E02), Sherlock remembers that Tessa knew John's middlename and this is how he figures out the whole thing about the Mayfly Man and his attempt to assassinate one of the guests.   I didn't really understand the connection between him dating the women and attending the wedding. I mean, he was the photographer, so he did not need a date for the wedding. And if Tessa was not invited, but only saw the photographer's invitation, why would the killer need to date those women?  So, what was the purpose of dating the various women?
Connection between the cases in "The Sign of Three"

In Fantastic Beasts and Where to Find Them, Newt restrains Graves' movements with one of his friendly beasts and then proceeds to use the Revelio spell to... (spoiler)     reveal Graves' true identity, who is actually Gellert Grindelwald.   My question is, what gave him away? How did Newt realize that man was not really Graves? I was thinking maybe the speech he gave matched...    Grindelwald's ideas   ...and also the power and skill he displayed whilst fighting the aurors. Does anyone have a better explanation for this? Also, as a curiosity, what did...    Grindelwald   ...do with the real Graves? Maybe something similar to what was done to Alastor Moody in The Goblet of Fire?
How did Newt Scamander realize "someone's" real identity?

The 1977 movie Close Encounters of the Third Kind is truly iconic, and one of my all time favorites. But there is one thing I am curious about.  During the climax, we see the aliens returning many people to the Earth. Most of them look like they are from a time far behind. Also, the other things that the aliens return during the movie are all very old things (taken a long time ago) eg.- Airplanes in Mexico, a ship in Mongolia. However there is one exception -- the 3 year old kid -- Barry, who is taken away by the aliens and returned back soon thereafter (at the end of the movie).  How did this happen? What could be the reason for this exceptional behavior of aliens?

Why did the aliens return Barry so soon, in 'Close Encounters of the Third Kind'?