Hmmm... That's a tough question to answer without going into spoilers. What I can say though is that there is a route that focuses heavily on the relationship between Ollie and Don, it's Route One on the flowchart if you aren't sure how to get there.
https://harmoyena.itch.io/beyond-the-harbor/devlog/129549/beyond-the-harbor-rout...
Let this devlog be your guiding moonlight.