The hired muscle isn't such a bad idea. Just say you need another pair of hands around your lab, and that's what I'm here for.

[He's certainly strong enough for it, even without his magic.]

As for how we met? Well, that co-worker of yours is already assuming we fucked, so you could say we met at a bar.

[He worded it like that specifically to fluster Viktor. But yeah, the "I boned him and now he's my lab assistant" seems like the path that will get the least prying questions asked, because everyone else would be too embarrassed to ask about it.]