Willbert: Goes by the name Will, this Diamond Dog is basically a merchant who sells legit gems and such that he finds himself at half price. He has a sort of a England-Irish accent. Also his top customer is Rarity due to her always needing more gems for her designs and the fact that she can't always go out and look for them herself sooooo, Will usually keeps his identity a secret by wearing a hoodie. Also due to his personality being a polite, kind, Generous, responsible and cunning type he doesn't want his customers to be in any danger due Will having some personal problems with the Diamond dog leaders, Fido, Rover and Spot. Some say it's due to one of Will's parents being a pony, others say it's because one of them was fox, but it remains a mystery. So Willbert travels across Equestria making a living off of the gems he sells to his loyal customers mainly from Rarity.
WillDash: These two are more of the "opposites attract" type which I can see that, Dash being the athletic stubborn Rolemodel while Will is the cunning responsible Merchant, these two are so different yet so similar. And both don't have to change each other/themselves for the other, Will can still travel around Equestria and Rainbow Dash can try to be a Wonderbolt or whatever she wants to do with her life. And they don't have to feel alone because Dash can easily use her speed to fly around Equestria and easily find Will on his travels and give him a big ol surprise hug. Not sure if they'll have any problems though, kind of a mystery.
MlpFim/Diamod Dog/Dash © Hasbro and Fausticorn
Willbert/AfterVerse © ME!