A usual-looking super mutant, Strong seeks to find the "milk of human kindness." This is a line from the play Macbeth (Act 1: Scene 5,) cited to him by Rex Goodman while trying to teach the super mutants about William Shakespeare's plays. Strong seems to have taken this metaphor a bit more literally and believes that if he can find the milk and drink it, it will give super mutants the strength that makes humans successful.
The Sole Survivor can free Strong from his cell during Curtain Call. After completion of the quest, he becomes available as a companion.
Eventually as his approval of the Sole Survivor increases, he will admit that he has learned to respect them.
Finally, once he idolizes the Sole Survivor, he will tell he has made the decision to make the Sole Survivor his leader, and his Berserk perk will be given, which grants +20% Melee Damage if Hit Points are below 25% of maximum.
Killing Enemies. (This mainly is silent, he will remark positive lines from time to time, but it is enough on its own to get his approval.)
Helping others. (Radiant quests mainly like Preston's repeating radiant settlement quests he will like upon choosing the bottom dialog when accepting/helping and is a quick way to get his idolization; Other "helpful" quests will be disliked.)
When being offered kidnapping radiant quests: "You're in luck" + "Teach a lesson"
When being offered raider troubles radiant quests: "Get to the point"
He likes when the Sole Survivor refuses to help Billy and dislikes when he offers to take him home. This behavior is probably set incorrectly. He even says: "Small human should be with his kind, this is good." while the message "Strong dislikes this." is displayed. He will also appreciate the attempt to convince Billy [his] parents are dead. Only trying to convince him once without pushing it can grant a like from Strong and keep the opportunity to complete the Kid in a Fridge quest
Strong's health is about 50-60 hit points higher than most other companions. Only Curie as a Ms. Nanny has higher health, at least until around level 50. Like most companions, he levels up with the Sole Survivor. His higher than normal health is balanced out by being limited to only equipping super mutant armor, which offers only moderate protection compared to higher-tier human armors, let alone power armor. The best available combination of super mutant armor for Strong provides slightly less protection than a full suit of unmodified basic metal armor.
Strong has the second best default carrying capacity with 200 lbs. However, his carrying capacity cannot be increased with armor mods since he can't wear normal armor.
Strong never goes into sneak mode and will prefer melee over ranged engagements, making him one of the most dangerous companions to bring around covert missions.
If Strong is dismissed without sending him to a chosen settlement, he will return to the lobby level of Trinity Tower.
When left in a settlement, Strong will often spend his time at that settlements Chemistry Station.
Unlike mutant companions from previous games like Marcus, Fawkes or God, Strong is far from civilized. He often criticizes humans, speaks of his desire for super mutant superiority and general carnage, and will even mention he wants "someone to eat" when hungry. The only thing that separates him from his mutant brethren is that he realizes that, if he wants mutants to have the same success as humans, he may have to work with them to learn their secrets.
Strong will give the Sole Survivor various meats much akin to the sweets that Piper gives.
In the quest Curtain Call, upon trying to interact with Strong before completing the objective he has set, he replies "Go Away, Bleeder!" which is exactly what Fawkes in Fallout 3 would say upon reaching him before the quest to retrieve the G.E.C.K. was initiated.
Strong believes that, when their time comes, the super mutants will eventually kill everything on Earth.
If Strong follows the Sole Survivor to give Virgil the antidote, he will join in on the conversation panicking at the thought of being "cured" and no longer being a super mutant where the Sole Survivor must assure him he will not be forced to do any such thing. This is ironic given the nature of the FEV forcefully turning him into a super mutant.
Due to the encompassing range of his dislikes, Strong can be a difficult companion to garner admiration from since most of these actions are sometimes hard to avoid when exploring ruins or negotiating with NPCs. Since he likes kills (and as all companions, time spent with the Sole Survivor), he is a good companion for a mapping trip while staying on the outside of places and not picking too many locks.
An easy way to gain Strong's admiration is to pick up the Cannibal perk and when doing quests that involve clearing out raiders from a location, eat the various corpses in the building. Saving and loading between corpses will allow the Sole Survivor to bypass the refractory period on gaining approval.
Defeating powerful enemies seems to give a lot of respect from Strong.
The quest Duty or Dishonor has an opportunity to gain four likes in a row for Strong during the final encounter with Clarke.
If taken to the corpse of the Sole Survivor's spouse, he will not say anything.
Strangely, Strong will occasionally voice his approval of the Brotherhood of Steel after joining, saying that the "metal men" are "worthy", even though he dislikes the Sole Survivor entering power armor and will lose a large amount of approval if he witnesses the Sole Survivor joining them.
Accepting Minuteman radiant quests from settlers gains a like from Strong, as well as choosing the "cocky" dialogue choice.
During Maxson's speech on The Prydwen, Strong will refuse to enter the room and remain outside, not entering until it is over.
Strong will voice approval if the Sole Survivor sides with the Institute and destroys the Brotherhood, stating that the Super Mutants can easily beat the Institute.
Strong seems to like the very first version of T-45 Power Armor, but disapproves of all others, saying "human look like robot." Currently unknown what triggers this; frame? armor pieces, and if so what ratio of new/old?
"Strong not care about stupid human stuff. Just want milk of human kindness!" – At The Castle
"Strange human hole. All metal." – Upon entering a Vault
"Strong learn new word. Strong learn 'respect."
"Human fight good. Human help Strong. Super mutants are brothers. Brothers share all. Not own things like humans. Humans share like brothers. Super mutants fight. Kill not talk. Human kill not talk. Human would be good super mutant." – Upon earning Strong's respect
"Old human junk. Worst kind of human junk." – Picking up pre-War money
"Goodbye Mack Ree Dee." – When dismissing MacCready to travel with Strong
"Stop fiddling. Smash!" – When crafting items or lock picking.
pc When asked about the relationship between Strong and the player, he will interrupt the player.
pc Upon sending Strong to a settlement with 0 population, water, and food he will vanish from the game after a couple of days. The only way to fix is to summon him via console command. [verified]
pc A possible fix is to build food and water and then wait several days. [verification overdue]
pc Another possible fix if a bed is not present is to build a bed then save and reload while away from the settlement (this was tested at the Red Rocket truck stop.) [verification overdue]
pc On some occasions, the message showing that Strong likes/dislikes this does not appear even when a certain amount of time for that action has past, thereby making it even more difficult to gain his Berserk perk. [verified]
This occurs at random times with other companions aswell, however the approval is still given just does not show. Using a save or 3 hour wait time glitch will still give affinity as normal. Not common but don't freak out if it does happen. Also applies to negative choices like lockpicking with strong or hacking.
pc Entering a suit of power armor can result in Strong's approval skyrocketing upward, despite the game saying he dislikes it.[verification overdue]
pc May become unable to move, and just kneel at the door where one enters a building spewing comments about the smell or whatever. Fast travel can fix this.[verification overdue]
pc Strong may be unable to move correctly when wielding a minigun. He will often stand in place when being attacked, uselessly pointing his minigun at the ground. One thing to note is the Gatling laser has the same effect but will happen less often.[verified]
Short-term solution: Select Strong and "command" him to attack "X." Basically pointing him into the direction of the attackers while he has a Minigun equipped will make him attack everything in that direction without aiming at the ground.