I've gotten the Affinity for most of my Companions and am working on the last one, Macready.

But I'm uncertain if there is anything to do that will gain Likes from him.

Here are the possibilities remaining:

1. He likes mercenary behavior, such as asking for more money to do a quest.

All companions like when you do minutemen radiant quests

He also likes it when you pick a lock that's owned (red) and when you steal. Most obvious places to do this are Diamond City and GoodNeighbor

I don't really like to do that as I don't think it's nice to steal things from people who are having problems.

Is there anyone else who deserves a good pickpocketing or professional thievery?

With all the groups of hostile enemies, there must be somewhere good for this.

Maybe at the Institute, since I am actively working against them.

But I don't know if it's possible to get in there without the guns blazing approach.

Would be so funny though, at the end of the day when all the Institute staff start looking for their wallets and can't find them!

And just for the lolz, I steal all the Synth guns and the legs of the last Synth I meet on the way out.

Have you done his quests? I took him along for the quests in Goodneighbour to clear the warehouses, and out and about killing stuff. Then after talking to him, he started a quest to go "talk" to those guys that were bothering him when you first meet him. Then we killed some more, the quest continued, and thats where I am with him now, at a hospital helping him get an item.

I did the mission chain about getting the medicine for his son, yes.

From this point onwards, I am assuming it is just about finishing the final steps, which usually means doing a lot of what he likes.

I'm uncertain if travelling around counts, although it seemed to for activating his personal mission, as it states you must have his company for a certain amount of time to trigger stage 1 and 2.

The warehouse ones I am unfamiliar with, the only missions I did relating to Goodneighbour are related to Dr Amari, the memory module and Curie's synth conversion.

Where might I find these warehouse missions?

I think stealing and pickpocketing might be counted as separate events. There's a murderer in Diamond City. You could pick the lock to his house as take something inside. If you're really dedicated, just either come back later or sit somewhere and steal something new every X hours. Usually, the cooldown for an event is finished when you sleep/sit for an hour. You'll have to test it yourself. I also never really liked the Cabot family so you could go to the Cabot house and steal from them if you're not already on friendly terms with them. Or from one of the warehouses with Triggerman in Goodneighbor. Or someone in general that you dislike in Goodneighbor, since there are a lot of sketchy people

It was the bartender droid in the club with the singer that gave the quest. Sorry, I'm at work and can't check the names right now.

You don't need to pickpocket, just taking anything with the "Steal" tag on it while he's your active companion will elicit a "Macready liked this" notification

Be wary though, his perk is bugged and is ridiculously overpowered.