Players will be able to have up to three in a party at a time, and all of them will appear fairly early in the game, preventing the "Eleventh Ranger" syndrome in some games (Legion in Mass Effect 2 being a perfect example).
As for making the characters more "organic", the game will rely less on numbers and more on reactions.
"For instance, we don’t want to have the Cold Jack simply count the number of times you’ve disagreed with her in dialogue before she suddenly becomes a (bigger) jerk. We want to have her relationship with you evolve," explains the developer, "Perhaps she and another companion have important matters that they need your help with right away—and if you pick his over hers, she’ll remember that... and that will impact your interactions with her later in your story. Regardless of your relationship with your companions, during combat you’ll have complete control over them. But whether they stay by your side throughout your journey may be a different matter."
Torment: Tides of Numenera is due to be released on PC in December 2014.