Vance permanently fused with Arden in a freak magical accident. At first, he hates and pities Varian in equal measure since his mere existence is the denial of his. Eventually, he sees that Varian is much kinder and more powerful than himself and at least the product is a good person.
Vance is one of Varian's components. He talks about Vance like he's a shitty mentor, recognizing both his sheer power and crappy attitude, but also holds a soft spot for Vance's dash of courage. (or recklessness)
Arden permanently fused with Vance in a freak magical accident, so he doesn't like Varian at first, but learns to accept his situation as a conversation in harmony rather than two separate entities. If he met Varian he'd be uncomfortable with how similar and different they are.