@Hiareualive well I’ve been seeing theories of Fyodor being a time traveler as well or even being from an alternate universe, but my person theory is that Fyodor might be multiple versions of himself and kinda just pops up wherever he deems necessary. Since someone pointed out that Fyodor might not have been acting when he tricked Sigma and stabbed him, he could hold like different versions of himself while not aging and time jumping as a vessel, if that makes sense.
Also if it the ship does cause a problem then really I’d either just stop writing it or even make it specifically clear they’re the same age, there’s not much to do in a situation like this :,)
(Also hello!! I haven’t seen you in forever! Welcome back!)