Reconciliation with factions (Fallout 4)

People who know how to measure themselves with such groups as Scavengers, Shooters (Mercenaries). I'm tired of constantly shooting and I'm losing quests. After all, they said that you can go through the game practically without killing people.
Spoiler: There were two scavengers in front of the castle and one of them was synth. I could talk to them, but as soon as the dialogue ended, they start shooting at me! What to do?