If Elodie wishes for a peaceful or even stable ruling, then she must earn approval from nobility and commoners alike. Elodie starts the game with 0 Commoner and Noble Approval.
There are also two other hidden statistics: Lumen Approval and Cruelty. The first only affects the epilogues, but the latter will lock and unlock many options during the game, add different text to epilogues and considerably shift Elodie's personality (and with it the tone of the game).
Spoiler Warning: Plot details follow, read at your own risk
Typically, Noble Approval is affected by your interactions with nobility, how much political respect you inspire and how much you support the local nobles. Interestingly, many actions that increase Noble Approval also increase cruelty.
Certain actions will displease some members of nobility. While this tends to have eventual consequences, it doesn't count for total Noble Approval (ex: It's possible to strip Brin of her title in Week 10 and still have an unanimous victory if faced by a vote of no-confidence).
If your approval is too low, you will face a civil war starting Week 29.
If Julianna is in the palace, partially pass a Sense Magic check and choose "Summon Julianna", pass a Composure (or Meditation) check, then a Wield Magic or Resist Magic check (if failed, test Flexibility or Reflexes+Running). Finally, pass a Public Speaking+Presence check to deliver an inspiring speech.
Pass a Sense Magic check and choose "Question him about the crystal", then pass a Resist Magic check
Win the naval battle (you will need high statistics in Military skills, having built naval ships and increased your number of soldiers, and high Wield Magic skill to pull this off; not losing soldiers in previous events and having high Climbing also helps).
When choosing a dance partner, dance with Linley ("Someone about your age")
When choosing dance partner, dance with Brin. Either pick "Someone scandalous" (Julianna must be absent and Brin must be alive and still ennobled) or pass a previous Court Manners and Intrigue check, pick "Examine the women" and choose Brin
If Banion asks Elodie for a dance, pass a Court Manners check and choose "I plan to marry you"
Pass a Sense Magic check, choose "Talk to your aunt", then "Offer her a court position"
To increase commoner approval, side with the common people during arguments, do impressive public feats, do charity and relief aid, and be reasonable (at least where people can see you). This makes it rather common for the player to be forced to side with commoners or nobles, so keep your approval in mind.
Many Cruel actions will easily reduce Commoner Approval. Curiously, they don't mind too much if you execute people as long as they're not righteous in the eyes of the commoners (the poisoner) or they don't get too see them die too brutally (the assassin of Week 16 and Kevan if you kill then with magic).
If your Commoner Approval is too low, you'll face a revolution during Week 39. This will end the game immediately if Elodie is not a Lumen.
If you receive chocolates, pass the check needed to choose "Save it for later", then pass an Intrigue and Poison check, choose "Test for poison". Fail the Medicine check and have a minimum of Animal Handling >10 so Elodie will test the poison on prisoners.
If your commoner approval is low, but directed your agents to look for uprisings:
Have Sabine around as a musician, choose "Stage a concert"
Pass a Herbs check, choose "Heal the sick", pass the first check check
Pass a Herbs check, choose "Heal the sick", fail the first check but pass the others
"Make a public appearance", pass any check
If you have money in the treasury:
Choose "Extravagant feast"
Choose "Respectable feast"
Choose "Small feast"
Choose "No feast"
Bear in mind that for Week 38, while choosing a "Small feast" increases Commoner Approval, it also causes a tragedy during the epilogue. Said tragedy doesn't really affect approval, but it can sour an otherwise optimistic epilogue.
This determines how willing are the novans to accept Lumen. Unlike other approvals, this only has direct effect on the epilogues.
First though, there are three initial branching points that determine if the player can alter the opinion on Lumen:
If Elodie obtains her crystal and transforms immediately, you can change Lumen Approval for the rest of the game
If Elodie obtains her crystal but abstains from transforming until the ending, you can't change approval but remain on good terms with Lumen. Opinion on Lumen remains unchanged and unlocks the "Lumen Crystal" and "Outcast Julianna" epilogues.
If Elodie constantly rejects magic and Lumen, you can't change approval but make your dislike for them known. Unlocks the anti-Lumen ending and "Lumen Rejection" and "Outcast Julianna" (if she lives) epilogue.
Bear in mind that you don't need to do too many increases to Lumen Approval to get the pro-Lumen epilogues. For example, accepting a magic tutor, avoid using your magic foolishly or irresponsibly and defeating Togami in a magic duel is requirement enough to get the pro-Lumen epilogues.
During judgement of the murderer, partially pass a Sense Magic check, choose "Summon Julianna", pass a Composure or Meditation check, choose "Wait for Julianna", pass a Wield Magic or Resist Magic check (or either Flexibility or Reflexes+Running checks), then pass a Public Speaking+Presence check
If confronted by Togami, choose "Accept his terms" as a Lumen, pass Resist Magic, Sense Magic and Wield Magic checks (or Resist Magic and Meditation checks), then counterattack with "Magic sword" (pass Swords+Reflexes check) or "Dazzle him" (pass Wield Magic and Decoration check)
If confronted by Togami and Selene is you magic tutor, choose "Refuse outright" to delay him and Selene will propose causing an earthquake to drive off the invaders, accept, this will have consequences later
If Elodie caused an earthquake the previous week, people start talking about the connection between Lumen and both the earthquake and the now-rampaging beasts of the forest
If Elodie had Sabine investigating the poisoned chocolates and Joslyn is alive, choose either "Decide Lucille is guilty" or "Ask about Charlotte's powers", then "Banish the entire family", Lucille will lash out violently when that happens
If Elodie and her circle sunk the enemy fleet with magic, a sea monster will rampage in the shoreline, regardless of the method used to appease it people are starting to blame Lumen
If Elodie accidentally summoned a Kraken, and chose to sacrifice Charlotte to appease it, people will call her an evil Lumen witch
This is a game-changing statistic that reflects how many capricious or sadistic actions Elodie has taken and is willing to take. It can be raised by certain choices and activities, and it both locks and unlocks certain choices and epilogues. See page for more detailed information.
Interestingly, many cruel actions in the game can raise Noble Approval. Also remember, not matter if it's in self-defense, burning people to death also isn't very nice.