Objectively the hardest achievement, well, to achieve in Fallout 4, Benevolent Leader is a high hanging mutfruit which bothers players to no end. But there is a way to achieve it without much sweat and with only ONE Settler and this is how to do it.
The best way to do it is in a small settlement, like Red Rocket, so this guide will be based around that area. What you need to do first is, clear the area of any debris or clutter. It will make the whole process much easier and it will prevent from any (unintentional) bugs occurring. Now put one sleeping bed, one turret. You’ll need some fruit and some water but what is most important - the bar. It goes without saying that you’ll need a Local Leader level 2 perk to built the bar though, so keep that in mind as you need to be at least level 14 to acquire that. As mentioned before, you’ll need at least 10 mutfruit, but just in case have at least 20-25 ‘cause this trick may take some time. You’ll need about 20 Water bottles too. Put them in the shared Red Rocket inventory. After getting those things, increase the size of the settlement. You can do that by putting random decorations or containers. Just spam those things until the “Size” bar of the Red Rocket settlement increases to the point of becoming yellow.
Now to the settler - send one, and only one settler from any Settlement to the Red Rocket. Select the settler in the Red Rocket and order him/her to tend and work the Bar you built earlier. Oh, this trick may take some time, so as to increase the speed of the tedious waiting, pop another bed for you to sleep in and skip time. So relax and keep sleeping in the bed. You’ll see the Happiness bar increasing in increments of 4, 2 and 1. This may take some time, but the wait is worth for that Benevolent Leader achievement. So just wait. Pop some Netflix or play an Android game, ‘cause again, this may take some time. Sleep again in your Fallout 4 game. Rinse and repeat. After 10 to 30 (or even more) minutes the Happiness will reach 100 and you’ll get your Benevolent Leader Achievement.
