My personal favourite is the "it's (not) normal?" accidental reveal--where whumpee does/says something or reacts to something in a way that they view as normal due to trauma, but that everyone around them sees as shocking/disturbing/impressive/etc and it leads to conversation.
- Hypervigilance resulting in seemingly superhuman reaction times (their reaction time was normal, but they were the first to notice by far)
- Paranoia/trust issues and related habits (double checking others' work, not trusting without verification, memorizing the position of items in a personal/private space to know if another person moved something/intruded, etc)
- Remaining calm and level headed during an extreme stress situation, where even the most level headed of other characters starts to lose their grip a little; bonus points if the whumpee is known for being anxious or quiet most of the time and suddenly steps into leadership only during the streeful situation/emergency
- Reactions to injury/illness (self isolation, self treatment, hyperindependence even to a harmful degree)
- Reactions to mistreatment (not seeing it as a big deal or realizing why others are so upset at how whumpee is being treated/spoken to)
- Reliance on routines, rituals, or extremely specific habbits/ways of doing a task (must always check that doors are locked after entering a house, must always have their clothes folded in a precise way, etc)
- Specific habits/rules for themself around sleep, hygiene, or eating/drinking (not sleeping unless someone is on watch, must keep hair at a certain length, must always make sure others are fed before they start eating, etc)
- Actions that reflect a trauma-related viewpoint (such as self sacrifice from the view that they are more expendable than others in their group)
Also the opposite--thinking something that is normal/safe is abnormal/a threat, or requires a specific response from whumpee. This could be a reaction to specific words/phrases, dislike of physical touch, refusal to seek medical care, refusal of a resource (healing items, food, etc) if there is perceived scarcity, refusal to show or talk about emotions, etc