Here me out.
Famous Whumpee had a traumatic childhood. They'd grown up being told they are useless and worthless and hurt so much they still involuntarily flinch, despite it being years. Whumpee can deal with heavy scenes (the ones where there's shouting and crying and violence) whilst filming because if it's in the script then it's okay, because they can prepare themselves in advance by going over the script again and again, telling themselves it's all fake, a lie, just a scene, that's it.
But
The other cast members don't know about Whumpee's past. Why would they? Whumpee's very good at keeping it hidden. So during the scene, everything's going smoothly, Actor is shouting at Whumpee, and Whumpee acts scared and anxious. And suddenly, Actor starts going off script. Actor is stepping forward, still shouting, but now all Whumpee can think about is their past, the shouting before the hits.
And then, Actor's hands suddenly fist the front of Whumpee's shirt, and they pull Whumpee closer, still shouting, still acting unaware that Whumpee is this close to having a panic attack. The scene suddenly isn't something Whumpee can control, because it is no longer on the page.
The words Actor is yelling blur into a deafening roar, echoing the exact pitch of a voice from Whumpee’s childhood. The sudden, rough tug on their fabric completely shatters the fragile wall separating the present from the past. Whumpee's lungs seize. The studio lights feel blinding, morphing into the harsh glare of a room they thought they escaped years ago.
"Cut! That was incredible acting, guys!" the director’s voice calls out from behind the monitors.
The pressure on Whumpee's shirt vanishes as Actor lets go, instantly dropping the aggressive persona. Actor smiles, completely oblivious, and pats Whumpee on the shoulder. "Man, you look totally wrecked. Great reaction! Your face went completely pale."
Whumpee can't answer. Their throat is tightly locked. Their body is rooted to the floorboards, but every instinct is screaming at them to run, hide, and shield their face. But no, Whumpee can't do that. They have to keep their past hidden from everyone. So they smile instead. "Yeah. I didn't expect you to be so good haha."