I don't think she was as carefully built as she seems. Feels like if this was always the plan the character would have had a more constant presence throughout the game, but she disappears for a good few chapters and then returns with a very different personality, which could work internal logic wise, but just feels rushed narratively. I think she was probably just another option, then DPC decided she would work for the climax and repurposed her for that.
Yea Liam was pretty awesome, you could tell DPC thought a lot about the challenge of having a Male Best Friend in the game that both didn't feel like a romantic threat to the player, and was somebody we wanted to engage with.
Yes Megan is the presented as the "right" choice, hence why the game is written around her romance, and she's forced on you, while others you usually have to deal with obstacles, or can reject. Though i think the dev kind of changed their mind on this towards the end and wanted Melissa to also be another "right" choice(that's probably why the penuptulate decision is about choosing either person). Nonetheless Megan has the "best ending", with aspects of her ending being split between Mel and Rena, which honestly felt pretty tacky as i think 2/3 endings don't do the character's arcs as much justice as it could have(Mel's feels most relevant to her character arc).
