it's not my first takeaway from the game, nor is it my second, but A Takeaway I have taken from In Stars and Time is that I should not be shy about pouring the trauma sauce onto my OCs
that being said, I am still like... trying to put a finger on how SGE!Lucent's brain works wrt events that most people would consider traumatizing.
there are some "no shit that's traumatizing" things like being basically kicked out of his village at puberty, that have fucked him up as much as one would expect; and then there are things like "nearly died a slow and painful death from miscalculating a Body Modification Self-Experiment" where he's just like "huh. that was fun, actually. let's do that again!!" there are things that do fuck him up, like losing a patient he tried his damned best to save, but he recovers faster than many other people would and doesn't linger upon guilt or regret - he did his best with the knowledge he had and that was enough. it was the effort, the fight, that mattered.
I think the things that tend to be most traumatizing for him all involve isolation, confinement, and helplessness. as long as he's not alone with his thoughts, with the sensation of his flesh prison dying all around him, he's fine. as long as he can keep going, he's fine. as long as there's something, anything he can do, he's fine. he's fine he's fine he's fine
also I say that Lucent doesn't do guilt/shame/regret but I think they might actually just manifest differently for him
he fucked up when treating a patient and it might cost them their life. his mentor did horrific things and he might have unwittingly assisted in that research. it sucks, but he did his best with the knowledge he had at the time. regrets won't help. hating himself won't help. the river of knowledge only flows forward.
he just... needs to take responsibility. needs to do better, be better, so he can fix his fuckups, so he can fix his mentor's fuckups, so he can keep these fuckups from happening again, so he can make it all better. he knows he can do this, he knows. he's smart, skilled, and capable, so he just needs to keep going forward. as long as he can keep going forward, he's fine. he's fine he's fine he's fine--
(Savoulain, taking one of Lucent's wildly gesturing hands in his. pulling him into a hug. making him some soothing herbal tea. reminding him to sleep. tomorrow, they can talk about this. tomorrow.)
I think Lucent also just like. isn't very self-aware when it comes to having icky bad feelings. I think he's not even consciously in denial much of the time, so much as he's just, oblivious that he's feeling bad.
Like there are definitely times when he's feeling bad and he knows he's feeling bad, and oh, does he hate it when that's the case. And he'll try doing stuff to Stop Feeling Bad, even if the stuff in question is dubious and risky and impulsive. But a lot of the time, the Constant State Of Excitement he's in kind of masks and muddles the bad feelings. Like he is the kind of person to be morbidly fascinated by rare and terrible diseases, but that means he's already convinced that the reason he's up late reading about all of the horrible things it does isn't because he's worried about his patient and his lack of control over the situation. No, he's just fascinated by it. He's so close to understanding it! You don't understand! He's not up late brewing dubious tinctures to try on himself because he needs a distraction, he's just so close to a breakthrough!
(You know toxic optimism, the sort that tries to cover up the realities of pain? It's that, but specifically towards himself. Bad feelings are real and valid things... that Other People experience. Why would he have them? He doesn't have any reason to!)