Got a new plot idea. A variation of this.

The alchemist is on a journey. To The End of The World. They say the Golden Fruit is there. An ingredient so rare people thought it was only a myth.

What she didn't tell anyone was that she needed that ingredient to make a cure. A cure for her illness. It would kill her in a year if she didn't drink the cure beforehand.

That's why she made you, a homunculus. To help her in her journey, especially since she would get weaker and weaker as time passed.

They eventually get the cure. But then, they meet a child who have the same illness who needs the same cure.

There is only one fruit. 

She fully intends to sacrifice herself. But how about you? Would you just let your beloved master die like that?