There are a few guidelines I try to follow when designing companions (some of these are dependent on the engine and franchise).

- Combat/Challenge-viable. Any companion that can’t hold their weight and help support the home team in some fashion isn’t going to last long in the hearts of players (well, maybe a very forgiving few). This is something I learned way back in Fallout 2 when it became clear that Cassidy was far preferred over Myron, for example (and not just because Myron was an ****, which factors into another point below). It’s also a lesson I picked up while playing Final Fantasy III – every character needs to contribute to the mechanics and challenge mechanics in some fashion (whether combat or stealth or whatever the game’s challenge is).

- Companions should be optional. Whenever possible, the player should never be forced to take them or in the case of true psychopaths, even let them live. The golden rule is the companion should be a support character or a walking/breathing slab of target practice if the players don’t like or want anything to do with the companion.

- Next, assuming the players like the companion, the companion should serve as a sounding board for the theme of the game. It’s not mandatory, but there’s no better way to reinforce the narrative than someone who is walking beside the player for 70-80% of the game. This worked well with Kreia in Star Wars: Knights of the Old Republic II, it was the spine of most of the companions in Planescape: Torment, and it worked well with Kaelyn the Dove in NWN2: Mask of the Betrayer. [...]

So in terms of companions for Project: Eternity, the process works like so:

- Establish the game mechanics for the title, and when possible, link that into the lore and narrative while you’re doing it. What’s the central system mechanic of the game? (For example, in Mask of the Betrayer, the soul-eating mechanic and basic combat were the two principle systems the player was interacting with.)

- Design characters that support that game mechanic, and if it’s been properly integrated with the lore and narrative, make sure they discuss that angle as well, either though exchanges or reactions to it taking place in the environment.

- Next up, figure out exactly where that character shines in terms of the game mechanics – why would a player bring this companion along? Are they a tank, a healer, or perfect for sniping enemies from a mile away? This shouldn’t overlap with another companion’s specialty if you can help it.

- Build a barebones background. Were they once a scout, an assassin, a merchant, a Sith Lord, a smuggler, a bartender, etc.? What led them to that… and what led them to where they are today in the world? I say barebones, because I prefer to leave wiggle room for exploration and fleshing out the background while writing the character – the most likely avenue a player has to discover a CNPC’s history is through talking to them, so I let the CNPC do most of the work and try to focus on giving the details there and then. [...]​