You brought Sampson home at only nine weeks old, right? One of the reasons Yorkies should stay with their mom and littermates until 12 weeks old is that they learn very valuable lessons in socialization. Sampson missed three weeks of lessons on puppy manners, including how to play nicely and gently with others. His mother wouldn't have put up with his antics and would have reprimanded him.
Poor Sophie. For now, you must make sure she has her own space and alone time so she does not have to put up with this bad mannered (but 100% normal) puppy.
Since he doesn't have his littermates to play with, make sure you play with him a lot. Get him some age appropriate toys. You will probably have issues with bite inhibition since he was taken from his mom too soon, so you will have to work on that with him. If he gets too rough, do what his mom would do, ignore him. Give him a time out. He will learn that all the fun stops if he bites and plays too rough.
Relax. He isn't aggressive. He's just being a puppy.
