It depends on the main character, how he will grow in the story, and how you want to show his transformation. What kind of person is the main character?
The way he interacts with the other characters, although he has a relationship with a princess, he seems to be somewhat of an average joe (who might eventually grow into a hero type figure), who in the beginning of the story so happened to be at the wrong place at the wrong time but got out of it only to face more problems.
Is the way that you introduced the main character relevant to how you wish to depict him? Nothing yet seemed to stand out about him other than the fact that he has a relationship with a princess. There are other things that may seem coincidental about the main character because the audience might not know enough about him before the first big problem occurs.
Since the story is action/adventure/fantasy, maybe it can start out in the middle of an action scene, or in the middle of a fight scene involving the main character. The scene might be a flashback, (a flash forward), the battle scene before he makes it back to the princess, a dream, a premonition, a bloody scene showing exactly what the enemy teams are capable of, etc.
You could give more information on the main character through his interaction with other characters and reactions toward any events. We want more information about the main character in the beginning not just to help understand the story and move it along, but to make the main character immediately likeable. A way of making the main character more likeable is showing one of more characteristics about him that the audience can relate to.
Also, is his fight just about staying alive, is it just about getting back to the princess, or is there more? Another idea is to give more attention to the kind of relationship the main character and the princess have and to get the audience more involved as to why it is very important they reunite.
If I said anything that was completely off, please forgive me and post more excerpts
You mentioned that it was action/adventure/fantasy. What kind of fantasy? Are there fantastical creatures?
May I ask why you chose these names/titles: August, Brianna, Outlanders