Everyone I'm going to give an example of what are list of NPCS and PCS. As what you can use and cannot use for newer members that join and are unknown to these terms.
NPCs [Non-Playable Characters] - Help move the character's storyline, but cannot train, teach or be taught techniques. They cannot be used to gain items, techniques or etc. [Ie. Mangekyou Sharigan]
PCs [Playable Characters] - They share their own trainings for daily, they can train, teach or be taught techniques. They can also have their equipement changed. There are two types though, as your first character is a PC so is your second and third however they follow the rules of a NPC, they cannot be used to obtain [Ie. Mangekyou sharingan]. Best example your first character cannot challenge your second to DM to obtain the mangekyou sharingan.