My younger brother and his pup live with us. So we have Levi the Yorkie and Dallas the Whippet mix...and they are quite the dynamic duo.
Levi is the Dominator. He is super outgoing and friendly, but he totally likes to let Dallas know that he is the boss. If they are at the dog park together, for example, Levi will play with other dogs...but interrupts if Dallas is making a new friend. If we call Dally's name, Levi thinks it is his duty to round him up and herd him toward us. He loves Dallas, plays with him, and cuddles him...but he's totally the boss of that relationship.
Dallas is the Protector. He's a total sweetheart, and I'm pretty sure he'd take a bullet for his little Yorkie friend. He plays gently with him, shares his toys, and lets Levi eat from his bowl. He goes along with whatever Levi wants to do.
This picture totally captures their relationship. They are never far from one another.