GreedFall

You must have a reputation with the factions that is not in the friendly stage. It must be nice reputation or below. When addressing the quest that asks you to form an alliance with the factions you must have some factions reject your offer.

I had to do a new playthrough. The only sidequest I did in the playthrough was to help the guy in the village with Dunncas and help Aphra since her quest deals with him a lot. I attacked everyone else I could, except the natives to make sure he would accept being high king.

I just got this achievement with these faction status

Congregation of merchants suspicions
Bridge alliance nice
Thélème Suspicious
Coin Guard friendly
Nauts friendly
Natives friendly.

You can get the achievement with 2 suspicious and a nice.

If you're going for the 3 treason related achievements this one is fairly easy as well. I didn't do any of Kurt's side quest, then saved hikmet during treason. I also avoided any of Petrus's to avoid any Theleme reputation. I did all of the side quests for the Natives, Nauts, and Bridge Alliance leaving me with 3 of 5 for the final assualt.

You only need one to not be Friendly (outside of the Congregation, obviously, because that is scripted). I had everyone Friendly except Coin Guard that was Nice, and the guy rejected my offer. As long as all 5 factions aren't Friendly, you're good.

The status with the congregation is not automatically friendly because it's part of the main story line. That is the only one which is suspicious on mine.

I had all factions as Friendly except Nauts (they were Nice), and they rejected my offer for the alliance, but the achievement didn't pop. I don't get it.

Likewise, managed to get my rep with the Nauts down to Nice but achievement didn't pop. Looks like it has to be a different faction.

It is probably not a good idea to complete all but the final step of the final side quest of your chosen neglected faction, for me it was the Bridge Alliance, I believed that leaving the final step of the final BA side quest would be enough... but it wasn't.

Two things put me over the threshold and into "friendly" status, one was the main quest where you defend Hikmet from Constantin's beasts (I even chose to not find the caravan before seeking the corrupted guardian, depriving me of +2, but it was not enough to keep me under).

The second thing was Burhan's apology for listening to the de Vespe slanders against your family, without doing anything, simply talking to him gave me +2.

Maybe it was the latter that put me over the edge.

My advice, completely neglect and betray at least one of the main factions (BA or Theleme) constantly to ensure this works.

After spending hours on this only to find I am screwed, I think I will leave this achievement to my female playthrough.

You only need to fail one of the five alliances during the recruitment mission just prior to the final main quest.

I found it very easy to remain "suspicious" to the Nauts. Don't do their quest line and they won't join you in the battle. I did all of Vasco's side quests and were friendly with him and it didn't change their stance the slightest.

The Coin Guard was also suspicious but I had done two of Kurts side quests. When asking Sieglinde she still offered to help despite the suspicious status. This probably has to do with gratitude towards Kurt - and most likely it didn't help that I had Kurt in my team when I spoke to her. So: Don't rely on the Coin Guard not helping your cause for this achievement.

I was Friendly with Bridge Alliance, Thélème and the Natives