4 other darkins

Inspired by the red mercy video "darkin theory" I believe that Vlad becam a darkin when he killed his master as the final test explained in his lore the lore states that every ounce of blood was fused with Vlad which could mean that the power of the previous darkin were given to Vlad. Another thing that supports that Vlad is a darkin is his use of blood as energy and power as well as he is technically using a living weapon that consume the life of enemies much like aatroxs sword. Any thoughts on this