Ben and the Frenchies
We’ve seen two sets of non-others go into the temple: the Frenchies and Ben.
The Frenchmen emerged different. Notable differences:
-Some degree of understanding about the Island: “It’s not a monster, its a security system protecting the temple”
-A silver tongue of sorts, manipulative skills, and the ability to bluff whatever emotion is needed at a given time: Robert calming down Rousseau with lies about love, their baby, etc, until she put the gun down and he made his move.
-Killing. Whomever they need to: Robert trying to shoot Rousseau
We have seen Ben exhibit similar behavior.
-He seems to have an understanding of many of the island’s mysteries
-He can hide his true motives impeccably, and uses his words to manipulate almost everybody.
-He has gassed his father, tried to shoot Locke, ordered the Others to kill the survivors, Ordered Sayyid to kill many Widmorians, threatened to Kill Penny, (Possibly killed Penny or bloodied someone on the Doc), Killed Keamy, sent Goodwin to his death, etc. He does not shy from killing.
I hazard that whatever happened to the Frenchmen is the same thing that happened to Ben