Lúthien is completely welcome, of course. Does Lúthien know all the people who might go into accelerated perception and keep Loki company? What are they like?
There was apparently some coordinated effort to share experiences, in as much detail as people were willing, to find common threads, when they were rescued after the war. Mine was atypical in terms of personal attention from Thauron and Morgoth, but not atypical otherwise. So he hasn't changed his tactics too much, which is interesting - we don't know enough about how the mind-control - the kind everyone's scared of, the enemy-sleeper-agent kind - works. Some people are very insistent that it's just people who've been in a simulation the last hundred times getting tired of this one and not assigning even the smallest chance that this one's real.
Seems like a conservative explanation, anyway, although I'm not sure where snapping and killing people comes in.
Fëanor's a hard bar to clear, honestly. This is fine. Socializing isn't her primary outlet, she only needs some.
Then she will last all eight weeks / six months and pop out again to say hi to people who live in sidereal time.