whumpee who was extensively sexually abused on some kind of captivity or ongoing situation they had no ability or power to leave, or by people they had to be around and were made to feel they couldn't say no to. they're deeply traumatized, and it took them a long time to trust their new team/friends/the people around them now. but they do. they trust those people, they know they're safe, and even when they don't know, they're helped to remember with reminders, with ongoing, constant proof every day.
and then they run into someone they knew before, back when it was bad. maybe it's someone else who was being abused in the same way, or someone who knew what was happening but also couldn't stop it for reasons out of their control. and this person regards whumpee's new people with nothing less than unbridled suspicion. and whumpee is the one to reassure them - it's okay. it's not like that anymore. they... they're good to me. they take care of me. they trust me, and i trust them. nobody- nobody fucks me anymore. nobody makes me... do things. they're safe. i'm safe.
all the while their new team/etc watches, astonished. maybe they didn't know the extent of the abuse. maybe they didn't know anyone else knew. maybe it's just shocking to hear whumpee discussing it so openly, and professing such profound faith in them, such trust. they're determined to keep earning it - keep deserving it. they're going to keep proving that everything whumpee said was true.