I have no clue what you guys are talking about o.O
Part of the Type-Moon setting; the Holy Grail War.
People with magical abilities compete for the prize of a wish granted by the Holy Grail. To take part in this competition, each magi summons a Servant; a "heroic spirit" from history / myths / occasionallymaybethefuture to fight for them. Each Master/Servant kills the other Masters/Servants until they're the only ones left.
Servants are grouped by their abilities into 7 groups;
Saber (fast, powerful melee)
Lancer (very fast melee specializing in long-reach melee weapons such as spears)
Archer (proficient with projectile weapons, can function away from their Master longer than other Servants)
Rider (very fast, very powerful Noble Phantasms (finishing moves/limit breaks))
Caster (magical abilities, can alter reality within a limited range)
Assassin (great stealth but poor combat skills, typically target Masters directly rather than Servants)
Berserker (any hero that went berserk in their lifetime, has a special ability that trades their sanity for a massive power boost, usually resulting in them killing their own Master as well as other targets)
Servants tend to keep their identities secret because knowing their past could reveal secrets about how to defeat them (Achilles' heel, etc)
Misao likes
Medusa (Rider-class from the 5th Grail War (Fate/stay night))

Ohji likes
Francis Drake (Rider-class from the Moon Cell Grail War (Fate/Extra))

and I like
Cu Chulainn (Lancer-class from Fate/Prototype)

Nero (Saber-class from the Moon Cell Grail War (Fate/Extra)

and Shakespeare (Caster-class from the Great Holy Grail War (Fate/Apocrypha))
