"Mother and Son"? Do you tag something like that based on appearance or for what it really is?
Because Arturia is Mordred's father (he even refers to her as 'father') because Morrighan took advantage of period of being a futanari and Saber was pretending to be a man.
Eriance said: I'm confused, is Saber the father or the mother? Rather, which one had the penis? Saber or her 'queen'? D:
She's the "father", but like littletiger and ithekro said, There's a period where Arturia has penis with Merlin's magic (the exact circumstance is unknown though), and Morrigan took advantage it by making a Homuculus, AKA Mordred from her sperm.
Mother and Son because other than that, Arturia is female.