Story Hints

For those that don't know. Edgy Alfonse is Lif, as said in the video.

However, Lif was the first King of Askr, so they're related. As such, it means that they look alike because they are literally family.

Another good guess would also mean that Thrasir (or whatever her name is) is literally Veronica's great ancestor. In which case, the greatest generals of the undead are the first human King and Queen. Which is pretty cool.