Fallout 4

Probably the easiest companion to get this with is Codsworth. You can find him in front of your old home after leaving the vault, pretty hard to miss.
Now Codsworth loves it when you mod your weapons or armor. So every time you visit your preferred settlement to mod something you will make (^{or at least have a chance to make}) Codsworth happy. Note that it has a cooldown until you receive a new like from him.
Old method, obviously patched, sadly:

If you want to boost it you can go sleeping for 48h and then mod something again and receive a new like from codsworth.
If you pay enough attention you can see a popup in the top left corner of the screen once the relationship increases. There are several stages of how much he likes you (^{neutral->respect->love->idolize}). Every time it increases he will start a conversation with you by himself if he's somewhere around you.
If you have him at maximum it will net you the perk 'robot sympathy' which gives you +10 damage resistance for energy weapons from robots.
In case you have him with you as a companion, he also likes generosity, giving away items and nice or peaceful behavior.
What he doesn't like is selfish behavior, murdering non-hostiles, picking owned (^red) locks, speech success, pickpocketing and theft.

If you don't switch between already owned mods you can make progress towards the 50 weapon mod achievement while increasing the relationship with Codsworth;


if you want to maximize any other companions relationship, you can find a list of what they like, what not and what perk they net you on this site;
http://www.gameranx.com/features/id/31624/article/fallout-4-...
note; sometimes it happens that you have to do something your companion doesn't like or you do it by accident and haven't saved your game recently to just load it and have it undone. But that's no reason to worry, it will not prevent you from reaching maximum relationship with them, it will just take a bit longer (^{except you do something to make them hostile like murdering them or someone friendly, try to avoid that} ).


*if you're going to vote negative please tell why in the comments so I can improve the solution if needed (^{in case something gets patched or anything alike}), thanks!

Thanks to TonySki for spell checking the solution by putting it through Microsoft Word spelling and grammar check!

I found it very easy to do with Cait. You will meet her in the Combat Zone (you will eventually get a miscellaneous objective to investigate there, by overhearing a Diamond City guard, I think).

Now, just totally undress yourself and fast-travel between a few locations (I fast-travelled to Goodneighbor, Diamond City market, Sanctuary Hills and Abernathy Farm). I chose settlements because you are safe upon arrving there. Each time you arrive at a location, and you are naked, Cait will like it.

Even better, if you stock up on booze and chems, if you drink alcohol or take a chem upon arrival at a location and waiting a few seconds, you will get a second like in most cases (beer doesn't count).

With this method, you will get 1-2 likes every couple of minutes, making this, I believe, the fastest way to improve a relationship with a companion. It took me only around 45 minutes to get Cait's personal quest, and another few minutes after I completed her quest, to reach the maximum level.

Edit: alternative solution with McCready, who you will find in the Third Rail in Goodneighbor. He likes when you steal something. Find a good spot for stealing (for me, the best one was the USS Constitution). Make sure you won't be caught by NPCs. Then, steal one item, Mc Cready will like it. Save and quit, reload your save, steal something again, rinse and repeat.

SPOILERS: East North-East of Diamond City, South of Boston Common is a bar/fight arena called the combat zone. I received it as a miscellaneous task to go check it out. Upon arrival I killed all the bandits inside to "save" the owner and a female fighter named Cait. Go through the dialogue and get her to join up with you. She enjoys it when you drink, do drugs, steal things, pick locks, and always taking the moral low-road. It only took several hours of traveling with her to go through about four dialogues she initiates after you keep getting her favor up with you. You will know you're almost finished after One more conversation after this and you will be given a tough romance option with charisma. I used grape mentats to boost my charisma, and ensure success. After she shares the mutual sentiments , you will have full relationship with her and achievement unlocked. (Also as Rubiodan mentioned in the comments, you still get the romance option as a female character)

The easiest person I've found to use for this achievement is Piper if you're playing a "good play through". She'll ask you later in the game on your opinion on what to do about her sister. Tell her not to worry and use the family option. Within a few quests she'll say thanks for you opinion and the achievement will pop.

You can get this as soon as you get out of Vault 111, when you make your way to Sanctuary.

After you have had talked to Codsworth move the story along, press "~" to open the CC window and click on Codsworth while looking at him.

It should pull up several digits in parentheses. The numbers isn't important, as long as you see some.

Type in "modav CA_affinity 1000". This should maximize his affinity with you. But in order to get the achievement to unlock, you need to do something else that Codsworth likes, such building/adding a mod to a weapon or armour.

Once you do that, you should see the message "Codsworth Likes/Loves that", if not, just sleep for 48hrs and try again. After that, go talk to him again. He should want to talk to you about something important. Achievement Unlocked!

Any questions and/or concerns, leave a friendly comment. Also to the petty downvoters; Go f#$k yourselves. That is all.

For reference; https://steamcommunity.com/sharedfiles/filedetails/?id=55523...

Just a heads up if you want to do this with Nick Valentine you will end up having to travel all over the map to find all the halotapes at the different police stations.Just writing to let people know as it takes a while.

I have completed this with two companions, Codsworth and Preston. Both like it when you make the "helpful" dialog decisions. In addition, Codsworth gets nice bumps in his affinity towards you when you make improvements to your weapons at a workshop.

Each companion will chat with you 3-4 times as you get them to like you more, and when you get the achievement, you will see "[companion] idolizes you" in the top left of your screen. Once you see this, do the final dialog with the companion for a permanent perk AND the achievement.

So this is how I'm doing it:

First make sure you have good hacking and locksmith abilities by unlocking their perks. (You have to unlock them anyways for their related achievements)
Know, to get Piper as your companion, go to Diamond City and she will be outside of Diamond City. Interact with her after and agree to help her out. She will then ask you for an interview, accept and she will become your companion. Make her your companion and as you explore the wasteland you will encounter many things to lockpick and hack. Piper likes it when you pick locks and hack terminals, so keep her around as you explore and after enough lockpicking and hacking you will get the achievement.

For some reason I couldn't get the achievement to unlock with Codsworth. I did this with Preston Garvey, which was almost as fast and also helps towards two other achievements you can't immidiately unlock with a console command (Community Organizer and Never Go It Alone).

Opening the console is different in every keyboard layout, check yours here if you're not sure:



If you're unfamiliar with Fallout 4, Preston Garvey is found in the first quest after leaving Vault 111, which you'll need to do for the War Never Changes achievement, anyway. First, talk to Codsworth in Sanctuary, right next to the vault. You then get a quest to go to Concord to see what's up. There's a fight and you have to kill some raiders.

After rescuing Preston from Concord and waiting until he arrives at Sanctuary, he starts to give quests to help settlements. When you've liberated the first one (Tenpines Bluff I believe), you can start to bring Preston along as a companion.

Take him with you. Open the console, click on Preston and type or copy/paste from here:

You can use the following command afterwards to see if it worked, should be at 1000:

Then, travel to the settlement in need (Greentop Nursery). If you haven't found it, the following console command reveals the entire map:

When Preston is with you, talk to the settlers in need and introduce yourself as Minutemen, be very polite. This caused the message "Preston idolizes you" and "Preston liked that" to appear, prompting his conversation about your friendship, even made the romance possible (if playing with a female character, that is). Achievement unlocked right after the conversation.

You can continue doing the quest for the Community Organizer achievement (this is the second out of three required settlements).

To make things even easier, use the console command for god mode:

And kill all hostiles in an area:

For those of your with a moral hesitancy to use the console unless the game has glitched, there's a very easy and fun way to get this if you find yourself preferring to adventure alone and therefore miss out on having a companion with you for most of the major side quests and conversation trees

Not only can you do it for one character quickly (which probably should be Preston if you intend on playing Nuka World right through so that you get his companion perk), but you can also quickly raise affinity for Codsworth, Piper, Nick, Curie, Hancock, Strong, Deacon, and Danse, as well as unlocking two cool side quests and a torrent of new dialogue where you learn about the histories of all the companions.

You need Automatron completed without killing the Mechanist/Isabella, move all the above companions to The Mechanist's Lair and keep one companion at your side for the passive affinity increase. Then accept Rogue Robot missions from Isabella. If she says she has no quests, immediately talk to her again and she'll have a quest for you.

Even though Isabella is usually out of the workshop area when you interact with her, all companions in the settlement will like you accepting this quest. The quest itself is simple and fun. The robots are always weird and varied and fun to explode, the mission ends when the robots are killed. ALL Rogue Robot quests appear outside of any cells, allowing direct fast travel to Isabella without the need to enter any other cells. And as soon as you return to her, she'll have another quest for you (even if you have to talk to her twice) and you can get everyone to like you again and just continue this cycle.

The quest also spawns in familiar random encounter locations, so you'll often come across other factions entering the tussle, often killing the robot for you while you sit back and enjoy the show. I am at a stage where I have all major factions friendly with me, so it is a lot of fun seeing the Institute or BOS take down a particularly violent Tankbot for you while you sit back and reap the quest rewards. Though it is fun to shoot the arms off a robot myself, and then lure it towards the Synths when it explodes.

Also, add an armor and weapons bench to The Mechanists Lair, every 48 game hours, just by switching to lesser mod and then back again, you can get Preston to like it (weapons) and Codsworth to love it (both).

You'll spend several hours having a blast killing robots, earning an achievement, learning more about your friends, and racking up companion perks.

Why bother with a console? =)