Main Walkthrough

Like any good RPG, Child of Light has its share of side quests. Some help a friend in need; some prove your worth to perfect strangers; yet others simply lead you to loot. All are useful to your ultimate goal of freeing Lemuria from the clutches of vile Umbra, as they universally yield up rewards above and beyond what you'll find popping open treasure chests at random.
The quests listed below have been arranged by order of acquisition. As far as I know (feel free to tell me otherwise in the comments), they are all available at any time, and do not expire. Some of the more involved quests refer to other articles for more details.
Rubella's Plight
  • Location: Old Monastery
  • PC / NPC: Rubella
  • Reward: Tristis joins the party

The first side quest in the game, Rubella's Plight is also the longest-lived. You'll gain it upon recruiting Rubella when you leave through the roof exit of the Old Monastery. To complete Rubella's Plight you'll have to find her brother, Tristis, in the southwestern bowels of the island upon which the Temple of the Moon rests. Find him and he'll join your party.
Finn's Plight
  • Location: Capilli Village
  • PC / NPC: Finn
  • Reward: Finn joins the party

You'll gain Finn's Plight when he joins the party on your trip down the Deep Dark Well. Save the Capilli and Finn will join your party permanently as you leave Capilli Village, wrapping up the side quest in the process.
Pastoral Panic
  • Location: Capilli Village
  • PC / NPC: Avo
  • Reward: Tumbled Tourmaline x 4

Avo, Finn's grandpa, needs the grounds of his home cleared of monsters. Solve the problems of the Capilli, then speak to Avo in the center of town to trigger the quest. Return to Mahtildis Woods and look for a dump of a home to the east of the Altar. Once the quest is triggered you'll find three beasts prowling the grounds. Kill them and Avo will show up to give you your reward.
Achilles's Odyssey
  • Location: Capilli Village
  • PC / NPC: Female Villager
  • Reward: HP Stardust x 4

The NPC who triggers this quest is on the Tree of Thorns entrance to Capilli Village, though she won't appear there until you free the village from its curse. The woman's flying pig, Achilles, has gone missing in Windwheels, and she wants you to bring him home. Scan through this article to discover which of the pigs is the real Achilles.
Free Trade
  • Location: Town of the Bolmus Populi
  • PC / NPC: Adolphus
  • Reward: Strength Stardust x 6

Adolphus believes non-Bolmus are useless at trading, and he challenges you to prove otherwise. Speak to the ratty merchant on one of the towers above the town's marketplace to trigger the quest, then move from one NPC to another to complete its requirements. First speak to Adolphus, then to a scholar in Capilli Village, then to a Capilli on the outskirts of the Old Monastery, then to Bolmus in the depths of the earth below the Town of Bolmus Populi, then, last, to Adolphus again. 
Bolmus Inferno
  • Location: Town of the Bolmus Populi
  • PC / NPC: Bolmus
  • Reward: Magic Stardust x 2

One of the homeowners in the Town of Bolmus Populi has a basement full of monsters that he wants cleaned out. Dip through the door in the basement to find a small dungeon populated by a variety of fiery reapers, some floating freely and others hiding in chests. Kill them all for your reward. 
Robert's Plight
  • Location: Magna
  • PC / NPC: Robert
  • Reward: Robert joins the party

This side quest appears if you proceed to the lower left area inside Magna's body. Robert will leave your party when you find the Vault of the Bolmus, and he won't rejoin until you crack the vault open. Details for doing so are found in this article.
Oengus's Plight
  • Location: Forgotten Tower
  • PC / NPC: Oengus
  • Reward: Oengus joins the party

This side quest pops up when you reach the bottom of the Forgotten Tower. Oengus will leave the party, and he won't stay with you unless you brave the labyrinth in the bowels of the Tower and rescue his comrades. The full details of getting through the labyrinth are in this article, but suffice it to say that you must proceed through the maze by only going through doors that bear the same symbol as those that appear on the shields of statues found in the labyrinth. Oengus won't leave the Forgotten Tower until you complete this quest.
Cynbel's Secret
  • Location: Flooded Lands
  • PC / NPC: None
  • Reward: Tumbled Onyx x 6

As you skim along the Flooded Lands you'll come across a statue with a green crystal. Investigate it to trigger the quest. That done, continue with the game until you reach Lowest of the Low. Proceed through the area until you find a stone basin that triggers a cut scene, one room shy of a boss. Check the ceiling of this room and you'll find a secret passage that leads up to a gleaming treasure chest. Pop it open to end the quest and earn your reward. (You can also follow a series of green crystals through the preceding area to find the chest, but, meh. Cheating!)
Gen's Plight
  • Location: Piscean Village
  • PC / NPC: Gen
  • Reward: Gen joins the party

You'll gain this side quest immediately after defeating the Ogre guarding the entrance to the Lowest of the Low. Return to Piscean Village and speak to Gen in her small home, where you spoke to her earlier, to complete the quest.
The Lost Lights
  • Location: Lowest of the Low
  • PC / NPC: Elemental
  • Reward: Faceted Spinel x 3

The Elemental is old, and wants to depart this world. To this end it asks your party to go looking for three lesser elementals that linger at shrines throughout the world, two appearing in each major area of the game. One is a short ways west of the elemental in the Lowest of the Low; the second is outside and to the east of the Lowest of the Low, on the Cynbel Sea; the third is near the base of Magna in Windwheels; the fourth is on one of the islands of the Cliffs of Erin; the fifth is just west of Capilli Village; and the sixth is on the roof of the Old Monastery. This article will help you track them all down.
Main Walkthrough