Permanent companions usually have prerequisites and may not join your party unless certain conditions are met; these vary between potential companion NPCs and often there are multiple possible ways to obtain them as a party member. The game will not allow having more than a certain number of active party members; this limit is half the player character's Charisma level. For example, a Charisma level of 4 allows taking 2 companions. With the perkMagnetic Personality the Chosen One is allowed one additional companion over the current limit.
Once a non-player character is recruited, their dialogue menu changes to a list of tactical and combat-oriented options. New from Fallout is a "Combat Control" button in dialogue, which allows manual change of an non-player character's armor, weapon, distance, and tactics.
The picture to the right is the in-game dialogue box for controlling companions. For permanent companions, the options are shown as follows:
Use Best Weapon
At first, this seems to do nothing, because the companion originally only carry their default weapon. However, they can be gifted a better weapon (and ammunition, for guns), then the non-player character will make use of that weapon instead. Alternatively, the companion can pick up weapons found on the ground.
Use Best Armor
This control acts the same as the one above; equip the companion with better armor in place of their default one (if they had one), granting them the corresponding bonus to Armor Class (and Strength in case of any power armor).
Berserk - The companion will always attack, never fleeing from battle, no matter the level their health drops to.
Aggressive - The companion will attack while their health is in an acceptably decent range. If it falls too low, they will ultimately flee from combat.
Defensive - The companion will be more mindful of their health, running when they are injured, even if just slightly.
Coward - The companion will always run from a battle they think they cannot handle, regardless of the opponents.
Custom - There are six options with 5 sub-options that can be chosen by the player concerning the non-player character's disposition. The possible options for each is listed below.
It is interesting that most permanent companions are male, others have no gender specified, except Miria.
At numerous occasions throughout the game, the Chosen One may find their companions blocking the exit to a room. This problem can be solved by entering the companions combat controls and changing their distance to the player character, followed by entering combat, thus having them move away from the exit. More easiliy you can right click on them and choose the push away icon.