There are 7 tiers of reputation that can be acquired for each faction. For this achievement you need to reach the top tier of reputation with the Foundation. (Ally status)
The number of points required to reach Ally status is 12,000.
Tier 1: Hostile (-2000 points)
Tier 2: Cautious (-1000 points)
Tier 3: Neutral (0 points)
Tier 4: Cooperative (1000 points)
Tier 5: Friendly (3000 points)
Tier 6: Neighbourly (6000 points)
Tier 7: Ally (12000 points)
My suggestion when aiming for ally status would be to first complete the main story with the Foundation and split the gold with them in the final mission. This will land you in Friendly territory as cumulatively you will acquire around 4000 points of rep with the foundation for doing this. This will also net you the achievement;
From here you have 2 options;
Option 1: Grind daily quests and scouting for encounters.
You can gain reputation points for the following
- Daily: Vital Equipment - Complete the quest and either accept the reward (+200) or donate the reward to Foundation (+250)
- Daily: Retirement Plan - During the Raider quest, tell the former Raider to move to Foundation with a Charisma 8 check (+25)
- Daily: Photo Opportunity - Take the photos to Ward and decline the reward (+75)
- Encounter: Faction Vs Creature - Keep the Settlers alive (+10)
- Encounter: Faction Vs Faction - Do not fire upon the Settlers and keep them alive (+25)
- Encounter: Send people to the Foundation - Use charisma checks to send people to the Foundation
As you can see the majority of your remaining points will likely come from the "Vital Equipment" daily quest. Which may take upwards of around 32+ days if you were to complete this quest only, once per day. The daily quest takes roughly 5 mins so it wouldn't be too bad to just hop on each day to do this.
Option 2: Glitch for Daily: Vital Equipment
It is possible to perform a glitch to complete "Vital equipment" multiple times in a single session. It takes a little preparation and you must be careful in performing the steps to ensure it works as planned.
Here is a video I found on Youtube explaining how to perform the glitch:
In summary..
1. Find one of the Daily quest items spawned on the map and put the item in stash (I found the "Intrustion Module" over at Willard Corporate Housing as shown in the video.
2. Go to Foundation, get Daily: Vital Equipment from Ward
3. Remove item from stash, put item back in stash
4. Leave and join new world
5. Remove item from stash
6. Talk to Ward, selecting the bottom chat option for extra rep. DO NOT SKIP ANY DIALOGUE AS THIS FAILS THE GLITCH
7. Put item back in stash
Repeat steps 4 - 7"
