Rummaging in the dusty corners of my brain I come out with this--what do our characters need?
Maslow did a pyramid for survival and societal needs though he forgot the respiration part.
Rule of 7 for the basic survival limits: 7 minutes without air, 7 days without water, 7 weeks without food--take this as an average for a fairly healthy human--and the person is dead or real close to it if any thing goes past 7. Lack of air and there is brain damage then death. This is a bit more flexible for a person who has an extremely cold body temperature. Many ice water drownings are reversed because the body goes into a low maintenance mode, but again this time is limited. Humans are about 75% water- a lack of water and you have increasing dehydration, toxin buildup in the blood, and cascade organ failure. Lack of food makes the body consume itself to keep the heart and brain going. Fatty acids aren't replaced, the liver and kidneys shrink, muscles atrophy and without intense and proper caloric replacement--the point of no return...
Needs are physical and emotional health maintenance. I need water but I want a cup of coffee. I want a hunk of pumpkin bread slathered in quince jam (both homemade by the way), but I need to eat a healthier breakfast.
For sci-fi and fantasy--the space traveler needs backup oxygen, or methane or whatever the character breathes, and a delivered or grown supply of water and food. Does a mermaid suffer breathing the tainted waters around an undersea volcano?
Next up is feeling secure and protected--this is with others and or in a sheltering environment.
What is 'safety' for your character? Being in a clan? Alone in a fortress? Is your protagonist curled up by a fire with a large scaled friend who's ready to toast anyone who dares look in with evil intent?
The next step overlaps a bit for the needs of love and belonging. Dracula and Frankenstein's monster may ravage the countryside--but at the core--they want someone to love--and to love them. Once human, whether undead or a hodgepodge of parts, that need is still there.
Even if love is absent--then there is fear--and that is still recognition and acknowledging the monster as existing.
That's the next step--that others know you exist--for good or ill. An empress or demon god is nothing without subjects. The richest and most powerful person on earth needs to interact, to spend, to make more--to be visible and immediate for that self worth. Is that worth--real or false?
The very top, or last part--is know thyself, which often strips away all the layers and collections and masques built as defense, as protection as a joke that lives on, as a habit that feeds the illusion. What are you without the BMW? Without the trophy partner? Without the second home and the newest and latest gadget?
In India there is a sect called the Jain. The male monks wear nothing, the Jain Mothers wear only a white sari. They carry a broom of peacock feathers so that they may sweep the ground before they sit so that they can brush away any creature and not crush it. The only other thing they carry is a small water pot. They are celibate, their belief is extraordinary, and their joy unearthly. They preach to those who will listen, bless those who ask for it, and pledge their lives to help others. That is their need.