The Alchemist wants to know what everything becomes when it is taken apart. Blood. Bone. Breath. Spirit. Rot. Memory. Death. Nothing is sacred once it can be studied. They are not driven by cruelty. That would be easier to understand. They are driven by interest, and interest can be worse when it has no natural stopping point. The bottles are not ingredients. They are results. The Covenant gave them access to places most people only reach once. The Alchemist went there and came back with samples. The work is what remains.