Vampires will get 30xp and mortals 15xp extra.
And the way this will work for ties between characters if a mortal has Mentor they cannot know the player is a vampire, and buying said mortal as a retainer done later during character creation is 10xp. And the GM can have them do their own thing since there is no blood bond or other ties. So the character may have to do influence checks to get them to do something.
If the vampire has retainer for the mortal they will know they are a vampire if blood bound, naturally, but the mortal will not have as much free will. But if you want the most cntrol the Kindred must take this as the more potent character of the two.
Also note the Elder in the area is an Unaligned Daeva she will not mind most covenents save two the Invictus and the Lancea Sanctum are exceptions, neither she would trust. You may belong to them just don't let her find out.