During your journeys, you can also find companions. These are people, humans and machines that you recruit with either your skills or with a conversation. They cannot be controlled, but they will follow your party and they will usually help you in combat. This category also includes NPCs connected with quests, who join your party for the duration of the quest, and disappear right afterwards. Unlike them, the machines that you hack into and animals that you tame follow you until they die, or until you chase them away, if this is possible.
Your companions can offer you with various bonuses. In the case of non-combat-oriented, such as goats or cows, they provide you with a bonus to the attributes of the character that tamed them. Each animal carries a bonus to a different attribute. Bonuses can be no higher than +1, but you can simultaneously tame several animals. Combat-oriented animals , such as big rats or alligators, are going to help you in combat, just like machines and humans. It is possible to seize/tame machines and animals both before and during the battle, as long as the test for the appropriate skill is successful. This is especially useful in the case of fights against numerous opponents, or ones that are especially strong.
Depending on your strength, your companions will either serve you as a significant help in fight, or as cannon fodder, which is an additional pool of CON, of a kind. Wile it is limited in the case of animals, it is practically limitless in the case of robots, because you can fix them for free. All you need is sufficiently high level of repair. Humans and animals need first-aid kits and, sooner or later, you may run short of those.
Unfortunately, the lack of control over your allies can result in a situation, where your melee rangers are shot from behind by the allies in the back. Also, it may happen that a party member that is key to a given quest dashes too far to the front and is killed with friendly fire, or hit by a grenade. Your companions cannot be stunned and at zero CON, they die. Therefore, it is worthwhile to clean the area beforehand and then offer the quest-giver to travel with you. If this is impossible, it is best to stand between him and the enemies. Rangers can be healed and companions cannot. This specially goes for companions, whose quests require you o travel between individual locations, because they will participate in fights with random groups of opponents.
There may be many companions and tamed animals in your party. The condition is that the companion needs to be connected with a quest. In other words, if you encounter the Lecturer (Provost, in the Rail Nomad Camp), and then Vax (Abandoned Rail Station), who do not have any quests connected with them, and you decide to offer both to follow you, in each of the locations you will be followed only by one of them. After he dies, he will be replaced with the other one.
Out of the interesting companions, Vax - combat android is worth a mention. You encounter him in the abandoned rail station in Arizona. He does not have too many CON points (mere 50), but he has a powerful energy pistol that works well against humans and even better against machines. He always attacks in bursts and can perform two attacks per turn. The bursts are strong enough to deal with honey badger in a single burst, with a bit of luck. Additionally, he can be fixed endless number of times and receive a temporary bonus to AP, thanks to successfully used hacking. The rail station is a difficult location, mainly due to the shredders residing there, and Vax's AI can perform dumb maneuvers. Still, in fights in Arizona Vax proves irreplaceable. Using it appropriately means lowering difficulty all over the area. In California, he can be killed during the first random encounter, with an energy weapon used by the Children of the Citadel.