My character kills someone at the beginning of the story, in a dystopian future where death and horror are commonplace. I typed it out a while ago, but now I am having doubts about how he behaves afterwards. For context, he killed in self defense, sort of. He didn't have to keep hitting the guy that tried to shoot him and rape his crush, but it was a heat of the moment kind of thing. To avoid prison, he is offered an opportunity to be in an experiment conducted by a corporation that practically controls (most of) the world. Now I am aware that killing someone is traumatic for anyone who is not a sociopath, especially the first few times. My character lives in a world overrun with little tentacle bug monsters that everyone must kill on a regular basis or be eaten and death is commonplace, but to use that as an excuse for a lack of reaction to having murdered someone feels lazy. The biggest problem I am having, however, is that this is all explained when my character, in a strangely upbeat mood, tells another subject in the experiment about it, after having just met him. Just how strange does this all seem in the context of a...futuristic/sci-fi/dystopian/urban fantasy/cosmic horror novel?
Is it important that your character tells it in an upbeat mood? Do your character and that other subject like each other? If so, being in the same boat with the experiment situation, your character could feel some kind of connection to the other one and be prompted to get it all off his chest. Sometimes it is easier to confess troubled feelings to strangers because we do not fear their judgement as much as with familiar people. And fear of being judged could definitely be an issue after having killed in self-defence. Why does he lack in reaction? Does he have to? Maybe he's is very much troubled on the inside but suppressing outward reaction to it is his way of coping with a traumatic experience. Shock and adrenaline can make a person do things they wouldn't if they were thinking clearly. So he might be torn between feeling justified (self-defence) and the memory of what he was capable of doing.
Why does he tell it in an upbeat mood? Killing someone who was trying to rape your crush sounds traumatic for just about everyone, so I'm not sure why anyone would recall this memory in an upbeat manner. Also, why would he tell a stranger at all? It might be common place but probably not something to be proud of, unless he's a criminal trying to impress another thug, possibly both already in prison!? If he must tell it in an upbeat tone, does he actually feel upbeat about it? Contrast it with his internal world. Maybe he's just trying to impress the stranger but inside he's feeling sick just thinking about it.
I think you could play it as the character being desensitized to death/killing by proxy, which wouldn't necessarily make him unrelatable or unlikable, but for it to make sense he'd have to come across as somewhat emotionally deadened or otherwise fucked up, I think (we're basically dealing with PTSD, here). That definitely wouldn't jive with him being upbeat about the incident. At best I would think he'd be grim and determined about it. I'm thinking of the war vets I've spoken to / heard stories from whose outlooks are typically "it was me or the other guy," with an attitude that it had to be done, but they aren't especially proud or enthused. An upbeat reaction implies a breezy nonchalance about human life, which would be pretty hard, imo, to make into a core attribute of a main character we're supposed to root for. I'd definitely emphasize that it was self defense, maybe have him struggle with a sense of guilt vs the knowledge that there was no other way to protect himself. He might overcompensate with the affect of nonchalance, but I would hope to see an internal depth betraying that he doesn't actually feel that way one hundred percent of the time -- he's telling himself he doesn't care about it as much as he's telling other people that.
Have you read Brandon Sanderson's Stormlight Archives, he does a great job of having one of the main characters commit a crime. Don't want to give too much away fro those who have not read it. The first book is The Way of Kings.
In order for me to get this point right, I've actually had to sit and watch interviews and documentaries on people who have killed. It's not pretty. It's pretty disturbing, actually. And it really kind of depends on what kind of killer you are.
