Queen_EnchantedLuck
Normally I love the oil and water pairing but Archer just has a bad vibe with me. I love PruAus so I don't know why I didn't choose that pairing over Lancer and Saber. I think SaberXArcher is well beyond water and oil.
Well, depending on how you look at it there could be a number of reasons.
One of my favorite ways to pair up character is to think of them in a different scenario and see how that plays out.
For example, let's take the Fate/Zero cast from their fantasy/action genre and move them into a romantic comedy.
From there you can figure out where each character would fit it.
Saber: Female lead
Archer: Rich guy, wanting to force himself onto the female lead.
Caster: Deranged stalker
Assassin: That shady character that really doesn't do anything.
Berserker: Childhood friend who, due to certain circumstances became distanced from and aggressive toward the female lead.
Rider: Female leads reliable associate.
Lancer: Pretty boy that, despite being able to get just about any woman he wants, has taken an interest in the female lead.