Party Members! They valuable assets in video games, most notably in RPGs, but more often than not, you are given more than you need or can use. Sometimes the amount of possible party members borders on the ridiculous, Final Fantasy VI had over 30 party members (granted over half of which were temporary), but some are mild like Persona 4 which featured 7 possible characters to choose from, including yourself.
Players in Persona 4 of course control, their blank avatar who they name and whose personality is shaped around the player's decisions. Along the way players quickly build up their first full party consisting of Chie Satonaka, Yosuke Hanamura, and Yukiko Amagi (Depicted to the left). Of course, as the game continues players are given 3 more members to choose from, Kanji Tatsumi, Teddie, and Naoto Shirogane. But switching out any of your previous party members for a new one isn't exactly easy.
By the time a new party member comes into play you've usually become attached to your current party and having working strategies set up around their movesets, stats, and abilities. Some have no problem switching out the old for the new, especially in games like Pokemon where it's better to switch out a water type to a fire type to fight a grass type gym leader, but some people find a workaround to avoid such problems because they can't bear to change their party for some personal reason. So I want to know, what keeps you from changing party members in RPGs like Pokemon or Mass Effect?