Your Einstein sounds like my Fletcher in looks and almost my Dexter in personality.
My Fletcher is 9lbs, LONG and thin, his head turned whitish color and his body is steel blue. He is 100% yorkie. His brother Dexter is from the same litter, same parents and he is only 5-5.5lbs, hes compact with short legs. Fletcher's ears are VERY erect and Dexter's ears flop at the tips.
Fletcher is very friendly and will come up to anyone for petting. He is a little wired and nervous though at times... Dexter on the other hand is a shy mommas boy. He really just likes his mom to hold him and if other people are around (esp children) he wants nothing to do with anyone but me. He is also aggressive towards other dogs, whereas Fletcher LOVES other dogs. I usually just hold him and most people might try to pet him or just leave him alone when Ive got him in my arms. I don't try to force dogs on him or kids just in case he does try to bite. I don't think he would. I have trained them hard to not do that.
Here are some pics of my babies... the first ones are Fletcher, and second ones are Dexter.
