He's not a sociopath, he's just 200 years old.
Remember how the book started. He had planned to take a single ship out into unknown space just to get away from humans.
Louis is very different between the first and second novel. He showns clear lack of empathie at the start of the novel, this could be atributed to some sort of depresion in the form of melangolia. He does not care for his friends seeking solitude he sleeps with a women purly because she reminds him of a former wife. Very early on he show lack of empathie but not only for others also himself. He Challenged speaker to animals for a duel. thAftherwards he's thinking to himself that if Nessus want's to speak up for him he might as well let him.
He is a danger to himsef and others.Most things in the first novel are self centered.
The second novel however he does a lot of good for selfless reasons no longer does he protent to be a god. He actually helps people much to CHmeee disgust. He felt good it was only afther I read the book that i rimagend that they where on a timetable and had he decended to a flying city proclaiming to be a god and demanded the information. Then he would have skipped the grassland people, the solar flowers, the vampires, the machine people And 2/3 of his time on the ringworld. Like a firefighter breaking in in a flaming childrens hospital yust to make pictures with the kids in stead of rescuing them and that's basiclee Chmeee point (they are wasting time and he is right). Theres more important things to do.
So is he a sociopath probably not no but he is mentally ill and a danger to himself and others.
the last case against him is when they decide what they are going to do he is in the presence of the boy and the librarian and it's Louis that makes the decision? Why Louis? Given the options avaible shouldn't the boy and the librarian be at least given the illusion of the choice with Louis only jumping in when they choose the wrong answer.
As for Teela, he tried to leave her behind but it was made quite clear that she was an adult who was allowed to make her own decisions. She decided to go. She's not Louis' pet.
He did sell her to a barbarian looking for a magical place tough. I also believe he did this because he found a wet hole in prill that was considerably less trouble to have around. She was his pet kept for his pleasure discarded when he found a new one.
I think a lot of 200 year old people are going to think that a 20 yo isn't especially adept at estimating hazards. If Teela Luck hadn't stepped in she might have stayed on Earth at his suggestion.
a good time to have made a speech to teela on how dangerous the place was. And if she had percisted to spend some time prepping the abandond flying castle with at least a ford between her and the wilerness and hopefully a radio so when a second expedition came to could say hello or at least know where she was... Louis didn't care.
I think the ending could have been aproved in several ways .
Step 1 make the ringworlders decide abouth the fate of the ringworld the boy and the librarian where there they should have been at least offered the choice.
Step 2 I reread the ending the radiation that kills the 5 is endeed for fuel not power they needed hot protons the stepping stones could have provided the protons if the fusion devises split up the water atoms I didn't do the math but mass density of a ocean is that absurdly bigger then a solar storm.
A interesting twist in stead of increasing the mass for the ramjets increase the energy. This would temporarly deplete the the super conductor grid in the Scrith making all the flying buildings collaps to the ground. Destroying civilization but killing significantly less. A interesting dilemma killing 5% of the people versus making society collapse.
