If you exile a survivor, depending on their traits (more unpleasant, more likely to hold a grudge), they can reappear later ingame and attempt to kill your player or community members. This could be in a direct attack on your base, or random encounters whilst out scavenging. What would be even better is that the exiled survivor could start a community of their own and launch sieges on your base. There could be different options where you can offer them tribute to leave you in peace. And seeing as they knew your base as they once lived there, they could even send people to sabotage your facilities or even steal resources or mods. Missions could then pop up which see you try to get them back. It could even go as far as the exiled members new community persuading your allied enclaves to switch sides and remove their perks to you, which you can then try to win back. The way you react could lead to different outcomes and affect relationship statuses with other allies.