I understand the most profound and simplest Truth of all: Any time any of us reaches out, any time we pour even a drop of love, compassion, simple human decency (no matter how small; how seemingly insignificant) into the sea of earthly existence - we are, each and every one of us - the being called Mercy.
The impossible isn't a limitation, it's an invitation.
Ultimately, any character you write - no matter how fantastic or alien - is an extension of yourself. When our characters reflect the truth of our souls and psyches, they become real and compelling. The wonderful paradox is that the characters then take on lives of their own, separate from their creators. That's where the magic comes in.