Robot Sympathy

Robot Sympathy is a companion perk in Fallout 4.

Obtaining
To gain the perk, the Sole Survivor has to reach maximum affinity with Codsworth.

The quickest way to achieve maximum affinity is to head to a weapon or armor workshop. Make a save and attach a mod to any weapon or armor piece. You do not need to build a new mod every time, attaching one from your inventory works fine. Make a save overtop of the previous save after Codsworth has "loved" this action. Now reload that save, attach another mod, and make another save over top of the previous one. You can use quicksaves to achieve this and simply alternate between attaching a mod and reverting to the standard version of the part.

Do note that the adding an armor mod and adding a weapon mod is considered two different actions, so you Can do both, in order to reduce the number of saves and loads needed.

Each action "loved" will add 35 points to the required 1000 for reaching maximum affinity. Using this technique, with Codsworth starting at a base affinity of 0 it will require 29 weapon or armor modifications to be attached.

Effects
The player character gains +10 Damage Resistance against robots' energy attacks.