[quote=LittleWing]
The way I understand it is that Servant based on stories are actually possible but they are considered Shades and are weaker than Heroic Spirits.For example: If Arturia Pendragon and the Legend of King Arthur were both summoned by the same person in the same class, then Arturia would still have better stats than the Legend because she is a true Heroic Spirit while he is only a Shade of her.
[/quote]

Wouldn't work. Servants are [i]all[/i] based on stories. You can only summon a Servant whose legend is known about--differences between reality and what you're expecting don't mean a thing. You'd get Arturia. Kojirou isn't even a proper Servant (no Noble Phantasm), had no supply of mana, and couldn't leave a single location. Using wraiths would produce a severely crippled character.

... additionally, he [i]still[/i] existed. It's just that the role he was [i]playing[/i] didn't. It is impossible to summon something with no basis in reality, you'll just get the closest thing. If the Heroic Spirit exists, you get the Heroic Spirit. XD

Besides, if OC's are preferred, playing King Arthur in any form isn't an OC.