RM1 has very little information in English. I would never have known that your responses affected anything or all of what contributes to whether they'll join you if I didn't flip through the scans of the Japanese guidebook. I'm sort of translating the responses and quest sections as I go. Because it's as I go, I won't be done for... probably over a year, because I won't be coming back to RM1 until after completing D2 and Rebirth.
Ignore the colors on the cells. Those are just for my personal playthrough to mark what I've done.
Is there a skit (face chat) viewer in the late/post game where the titles of them are viewable? Going off of their Japanese titles makes it difficult to tell for sure which skit is which sometimes.
Some notes not visible that might be nice to have:
Confidence is a separate stat from evaluation, though it does contribute to it. You cannot check it in-game. It is increased by your responses, by winning battles with the character in the party (Through this, I have increased Stahn's evaluation to "good friend" before he even left Ailily...), and by completing quests issued by the character. It is decreased by losing battles with the character in the party, and canceling quests issued by the character.
Evaluation has more levels to it than the innkeeper's text implies. Certain skits only trigger at certain evaluation levels (or at least the guidebook uses the terminology that matches "evaluation" and not "confidence", so it could be the guidebook writer's error?), but I've had high-evaluation skits trigger while the evaluation given in-game hadn't changed.
A combination of confidence, evaluation, fame, and level discrepancy are what decide the likelihood of a character joining your party. (Though you can just leave and enter town over and over to try again until you beat the odds)
...Except in cases where that character is offering a quest, in which case they will never join your party when invited as long as the quest is actively offered. Example: Arche is temporarily offering a training quest. You cannot invite Arche unless you refresh the quest list and she's no longer offering a quest (yes, even though she immediately joins if you accept her quest). This also means characters like Kratos who issue the story quests are difficult to invite until you've exhausted all the story quests in that town, because those quests will always be on the quest list when you've gotten enough fame until they're completed (or you tank your fame I guess).
Similarly, only one quest can be issued at a time per character, so if you're trying to farm for Kratos's defeat-the-bats quest, it'll be difficult until that section of the story is clear because of story quests taking priority.
If I only relied on the information already available in English, I would have thought Kratos was just especially hard to win over. He isn't any more difficult than anyone else, it's just the quest thing