Companions carry much of the emotional weight in role-playing games, and they are among the most expensive characters to build. The reason is structural rather than literary.
A companion multiplies every scene
A character who follows the player must have something to say in places the writer cannot fully anticipate, across quests that may be completed in any order.
Each additional companion increases the number of possible party combinations, and reactive banter has to account for who else is present.
Teams control that growth by limiting active party size and by writing barks against situations rather than against specific quests.
Approval systems make relationships legible
Most games track a hidden value representing how a companion feels about the player, adjusted by choices made in their presence.
That number gates content. Conversations, personal quests and endings unlock at thresholds, which converts a relationship into something the engine can actually check.
Designers who expose the number risk players optimizing it directly, while hiding it entirely leaves players unsure whether their choices registered at all.
Personal quests carry the character arc
The companion story is usually delivered through a dedicated quest line that triggers as approval and progression thresholds are met.
Structuring the arc this way keeps it out of the main path, so players who ignore a companion do not encounter half a story with no context.
It also concentrates the expensive work, since a quest can justify unique locations and scenes that scattered dialogue never could.
Reactivity is the part players notice
What makes a companion feel alive is commentary on things the player did, particularly decisions made hours earlier in unrelated situations.
Implementing that requires the game to record decisions as durable flags and for writers to reference them, which is straightforward individually and enormous in aggregate.
Teams prioritize reactivity around a small number of major choices rather than tracking everything, because the illusion holds if the moments that felt significant are acknowledged.
Cut companions are cut early for good reason
Because a companion touches dialogue, quests, combat balance and cinematics, removing one late in development means unpicking references across the entire game.
Studios that cut characters therefore do it during preproduction, when the cost is a design document rather than a year of implemented content.
That is also why companion rosters rarely grow during development, and why post-launch companions are usually delivered as self-contained additions with limited reactivity to the base story.