I can’t sleep. Why? Because I’m paranoid. Paranoia isn’t healthy. Paranoia erodes (this would make a great band name). But after traumatic events, your brain cannot always process information normally or rationally, so when it sees/hears/thinks something that ordinarily would be processed/filtered in a rational way, it may respond and react in totally abnormal ways, such as paranoia. The brain is looking for patterns to emerge to link it to some sort of familiar (traumatic) experience, because it is trying to protect itself from a trauma to happen to it again (and thinks that finding other bad experiences will help).
The problem with this is twofold. First, these patterns are always going to be seen, because they are actively being sought, albeit not deliberately. Your brain is always looking to make sense of things that happen (in its own varying way), so when something traumatic (and therefore irrational) happens, it tries to connect pieces to make sense of it. The brain is going to see patterns everywhere; that’s what it does. Trouble is, it’s not going to make the distinction between rational fears and irrational ones when it’s in a seeking mode, it’s just going to build data. And even though people constantly claim that you should look for patterns (suggesting that seeing similarities will help you prevent mistakes from happening), there are a lot of problems with doing this. There are so many data points, it’s easy to focus on the wrong ones. You’ll grow weary of people with certain physical traits that remind you of [trauma/past], or other trivial non-causal items, instead of a relevant item. If someone chews gum the same way as the guy who shot your puppy, you’ll project that prior event onto them (things that set off these connections are usually called ‘triggers’). You may start to either use that data to absolve yourself of responsibility (‘it was all their fault, because they all did things x, y, and z’) or blame yourself (‘I should have seen that/prevented that/known’). When our brains are being defensive (either anticipating pain based on paranoia, or because something traumatic has just happened), the instinct seems to be to rationalize trying to find these patterns and to look for ‘wrong,’ which only makes the problem worse.
Secondly, looking for ‘bad data’ and previous trauma will only magnify any present situation and prevent healing. All of your brain’s focus will be on negative, detrimental items and will be unbalanced as a result. The best thing to do whenever the brain sees or starts to look for negative patterns (fear, pain, and so on), is to focus on ‘good data’ and dissimilarities (joy, laughter, etc.). This will help you separate and process individual events (therefore not cling to past pains or wounds) and avoid becoming delusional. It will also help prevent you from creating bad experiences through the ‘self-fulfilling prophecy,’ where you’ve projected your brain’s imaginings of ‘bad data’ being linear (bad thing A happened, so bad thing B happens next) so concretely that you become convinced that those negative things ‘must’ be true.
When you’re actively trying to find parallels to past pain, that’s something different. It’s self-sabotaging; that’s not protection, that’s persecution, and your brain might stay stuck in victim mode if you don’t take a hold of it. If you’re not aware that your brain is doing this (trying to find parallels to past pain to go ‘aha! Fight or flight!’), then you will keep wondering why things ‘always happen to you.’ You have to be aware of what your brain is doing (trying to protect itself from harm), and then show it all of the evidence that the past experience is not actually happening all over again, even if there are similarities. The best way to heal from the pain of the past is to stop expecting it to happen again; this does not mean to ignore warning signs of bad behavior, but to separate it from other events and show the brain how now is different from then (or this is different than that). Eventually the brain will learn that this situation is not parallel to the previous one at all despite whatever superficial (paranoid) similarities it saw.
I’m not suggesting that you should ignore ‘red flags’ or dismiss things off as merely being paranoia. Fear and paranoia can help us, so long as they are looked at as a guideline rather than as gospel. Once those elements start to control us (instead of us controlling them), that is when we need to take action.