Writing a corruption story like LotV, centered on a gorgeous women like Lily (and LotV is firmly in the corruption porn game category), to make the corruption process interesting, a writer would try to maximize contrast between between the MC and other characters to bring maximum effect. Also, the writer would try to create unexpected complicated situations and go for "chock" value. Complications are mild in the beginning of the game but get more and intense the longer the game goes on and the more corrupted the MC gets - the images are designed to tell that story to further maximize the effect.
These is a standard concept that are used by artists and movie makers like for ever.
What P and P has done is just applying these proven ideas to a porn game.
So all characters surrounding Lily are designed to play different parts of this story and to create these effects in various ways - again to create variation.
You can look at Fred as being maybe the most unlikely character Lily would fall for and precisely therefore he gets major role
imagine if he was a young handsome man in her age like Luke - it just does not create the same contrast or interest and the corruption process would be over by v0.1 or v0.3 tops - if falling for Luke even is corrupt...
The other pervs (like Rick, the therapist and the good doctor) are in the same category as Fred - maximum contrast, but they just play a role in corrupting her.
The library boy is there to create an interesting Milf/blackmail situation (young/old contrast theme again but reversed).
same goes for Mike - large contrast but he is designed to be likable - again to contrast with other men (and young men: Zach).
The fact that we are discussing this game so much is proof that they have been successful in their design.
Congratulations to P and P!!
