You don't have many life points in Greak: Memories of Azur, so knowing how to heal is half of the battle. There are mainly two to heal yourself, cooking/ingredients and red health orbs. One you can rely on fully, but the other may appear at clutch moments, but you can't count on it. You can get items that instantly restore your health, but these are pretty rare unless you buy them.
Most resources that restore health regenerates your life points. It does not restore it instantly, apart from a few. Cooking will be your main source of sustenance, but depending on what you cook changes how quickly your health begins to regenerate.
Food is separated into two categories—Cooked Food and Ingredients. You can eat most ingredients, but it takes longer to regenerate your life point than cooked food, and some don't give you any effects. A Veggo Root may take as long as 10 seconds to regen one life point, but a Yird Muffin will regenerate two life points in five seconds. In a life and death situation, having cooked food on you is always a boon compared to none raw ingredients.
There are two ways to obtain red health orbs. The first is from Red Crystal that can be found in random places in the areas. Upon breaking, these red orbs will fly out and heal whichever character you are controlling at that time. The second way is by defeating enemies, sometimes red orbs will fly out when an enemy is defeated and heal you, but this is not something you can rely on.
Can you/how to heal your other characters?
In short, you cannot heal a character when you are playing as another in Greak: Memories of Azur. The only way you can heal is by switching to that character and eating some food or getting life orbs. If that person has no food, you can switch to one of yours that has and drop food from their inventory for another to pick up.
To do this, select the character with food, open up your inventory, and highlight the item needing dropping. Then press Y on controller, or Delete on keyboard. This will drop said resource for the injured character to pick up, eat and regenerate health.
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