Sergeant RL-3

Sergeant RL-3 is a comical soldier created before the Great War who can become one of your party members in Fallout 3. The metal patriot can be purchased from Tinker Joe outside the RobCo Factory for 1000 caps. The player character can only buy if his karma is neutral. Otherwise Tinker Joe will just say Sergeant RL-3 "...doesn't like the looks of you."

Sergeant RL-3 has an experimental soldier personality making him, "unstable," and to only like particular characters (thus the neutral requirement). During combat he will also say things like "Another glorious day in the US army! Hooah!" making him quite a comical follower.

Sergeant RL-3 won't leave you if you get good or bad Karma, however if fired he can only be re-hired if you have neutral Karma. If you fire Sergeant RL-3 it will wait for you at Canterbury Commons where you can pick him back up for free.

Equipment
RL-3 can hold many items. In fact, his "storage compartment" has the best storage capacity out of all available followers. For example other followers could only hold 2 sets of power armor and a few weapons while Sergeant RL-3 can hold 3 sets of power armors and weapons.

Sergeant RL-3 cannot wear armor and cannot use human weapons.

Combat
RL-3 uses a weaker Plasma Rifle and when in close range it uses a very effective Flamer. He is extremely vulnerable to Energy Weapons, Big Guns and strong melee attacks like those from Yao Guai. Sergeant RL-3 repairs itself automatically after combat.

RL-3 CAN die, which is very costly to the character since he is 1000 caps. It is better to keep him out of dangerous situations, much as you would Dogmeat (Fallout 3). He does have a very high attack with the flamer, however, making him good for small party kills, i.e. Raiders, Slavers, etc.