It'd be kinda like the atmosphere in a company or something. When a potential "employee" shows up, I check their background (stats) and how they would be able contribute to the team (moveset) and then decide whether they're "hired". They're on a trial period until they really prove they deserve the job they've been given. Should they do well during that evaluation, I start getting attached to them, but not any more than to anyone else on the team, no favs. They also always run at risk of being replaced by someone more efficient. It's just business (mostly).