It was rather easy for me to get MacCready's perk. Although meaningless because I never use VATS. He likes violence for example. Immediately after ending his med quest I had the perk. It was not so easy to get him into my bed, Cait was more willing here for example. Anyway, from here you can have hints what companions like or not: https://steamcommunity.com/sharedfiles/filedetails/?id=553055452

Anyone know if the perk is supposed to add a flat +20 to the VATS percentage? Or multiply it by 1.2?

For instance. If the base VATS chance for a head hit is listed as 50%.
Is it supposed to just add a flat 20% to that number for a total of 70%?
Or is it supposed add 20% of that number for a total of 60%?

Reason being. If they intended for just a flat 20% addition. That might be why they did the plus 2000%. But, just forgot to add a function to cap the total addition at +20% flat add.

I use this head shot a lot now because...well, it's there. So what I did to balance things a little was raising the difficulty to hard, and I may go up a bit higher. You can also use a weaker weapon too to try to balance things.

Got that quest recently, but had already run into the cult and killed them all, so when I came to fetch her I just had to step over the pile of dead bodies and open the door, lol. I guess she hadn't noticed her boyfriend was dead =)

Yeah, when you kill them during the quest, she's still "Meh... he outlived his usefulness." smh lol women ^^

For the first time in 5 playthroughs I finally got MacReady's perk and romanced him.

Loving it for the time being, but, yes, I can certainly see what the issue is. I hit a Deathclaw Matriarch with a combat shotgun from about 200 yards. She was at 0 everywhere except her head. I can now see how it could be game breaking for some. Me. Not so much.

He isn't really glitched. You just have to do his companion quest.

The thing is his is kind of hidden. He is not the one that gives it to you. It is part of the BoS quest line.

If Danse gave you that post-CIT speech in the Airport or on the Prydwen, you missed your chance to do the quest that will allow you to get maximum affinity with him and he is forever capped at 999 affinity.