I really think Mel meeting Viktor in the magic realism AU would be one hell of a scene. Because they don't have a reason to cross paths in this timeline outside of Jayce. And unlike in canon, where Viktor is an asset, here he's competition for Jayce's time and possibly more.
He's a friend and a colleague and she doesn't know what they're up to, only that a lot of Jayce's attention is on this guy. And I think that would be an interesting conversation between Viktor and Mel on a first meeting as she is trying to size him up, figure out what is going on between them in that subtle way of hers while Viktor does not give her an inch. They have a talk where neither is saying what they want to say or asking what they want to ask, being on different pages, having the same conversation yet for two disparate reasons.
And in the end, Mel would come out on top. Not because she gets any closer to the research they're conducting in secret, but because she gets insight to the relationship she's up against. Insight neither Viktor nor Jayce have come to understand themselves.
Viktor would be left with a final reminder that his time with Jayce is ultimately short, and she'll be the reason why. Not out of malice, but necessity. Jayce won't break his Pact, won't risk ruining his family name, and if he isn't getting with her, then it'll just be someone else. At some point, his focus will align itself where it's supposed to be, and there's nothing Viktor can do to stop that.
For now, it reads to Viktor that their time working together, the project is ultimately on a timer, doomed from the start to be cut short as they both have to focus on their futures and what's necessary for that. In a few months, that conversation will come back to him, with an entirely different meaning.
