I've just finished rewriting an outline I wrote for a possible TV limited series. One of the most important things I do when I rewrite a rough draft of an outline for a screenplay or novel is to remove and replace the words "realizes" or "realized".
As usual, I found a few of them in my first draft. For example, the first draft might read, "He realizes that his supposed best friend is not on his side at all."
Potentially a powerful dramatic moment, right? What's the problem?
How do you show somebody realizing something? Do they get an "aha!" look on their face? Do they speak their realization to themselves? Do they just look pained? This is a particular problem for scriptwriters, unless they work on one of those telenovelas in which a character suddenly looks up and sees a flashback of a scene shown a few days or weeks earlier, with the sound featuring a slight echo this time. Then her eyes begin to glisten with tears: Aha! Rodrigo has been having an affair with Margarita!!! Cue big sobs and general over-acting.
In a screenplay we could show what leads to this realization so that the audience will realize it at the same time the protagonist does. Maybe the protagonist sees something on his friend's computer, or he is tipped off by someone else...it doesn't matter what it is, as long as it can be shown.
In a novel it's OK to say that a character realized something because novels do give us permission to be inside the protagonist's head if we want to, but even then it's better to describe the actions that lead to the character's conclusions.
However, we're not talking about writing the screenplay or the novel yet, just a brief outline. That doesn't give us room to go into details. Instead we just need to use words that suggest they are stand-ins for actions we'll see in the final product.
"Discovers" is a good one. Discovery is an active process.
"Finds out" is also pretty good. Again, finding or finding out suggest a process, not just a conclusion. We could also write, "He finds proof that..." Proof is tangible.
The best choice depends on the context. Here, courtesty of thesaurus.com, are some more that might fit:
It may be that you are writing about something that is a sudden thought, with no apparent process of discovery involved; in that case, "realizes" or "realized" may be the best word after all. In most cases, though, it's a good idea to look for alternatives.
(There are lots of useful tips on writing in my book, "Your Creative Writing Masterclass." You can buy it from Amazon or your other favorite bookseller.)