[@KoL] yeah it probably wont go very well, which is why I am interested in this. The meeting between the two could be very interesting I think, especially with their shared obsession and hatred of their own family's. 

[@VitaVitaAR] Yes the the world thinks that Mordred is a man no? The same way they think that Arthuria is a man. 

Right, but Saber was able to easily pick out Diarmuid and was able to slowly recognize Lancelot even under layers of deceptive magics. For a Servant who has no relation to her it would almost certainly be a slower process. 

For people not being prototypes of each other you are making that rule up out of nothing. Sigurd is a prototype of Siegfried, this we know for sure, I don't see what evidence you have for saying that the countless other legends that influenced neighboring legends dont also share connections to some degree.

I never said that they would think they were the same people. You just agreed with me there on your last line. I was never talking about reincarnation, which does not exist for Servants in the first place. Heroic Spirits are actually preserved as unique existences within throne of heroes, they are isolated from the cycle of reincarnation that everyone else goes through. That they would recognize their lives contained identical mythical themes would be the relationship I am taking about.