Primrose: this is so simple that the first time I played the game I thought I had to find something more. There is only one clue, you get it when she shows you the library's writing room (after revealing her large secret).
Revealing her dark secret involves multiple choice responses. If you need a hint: Primrose was Merek's other student, but she was not as talented as your character
Evelyn:
1. the second time you eat with Evelyn, you get a clue, and your character says he should check the family records for more information.
2. Ask Primrose to learn that the records are at city hall.
3. Search the records, and find a discrepancy in birth/death dates (someone born years after their parent died).
4. Talk to Aldred about what you found. You'll need to reveal his dark secret and remove his inhibition to get him to talk. He confirms your guess as to what it means, and adds details.
Once you've gotten confirmation from Aldred, you have the only clue you need and are ready to reveal Evelyn's dark secret. There's no multiple choice on this one - just choose the one clue and you're done.