Fate/stay night, Pandora Hearts Recommendations
Saber and Alice, (the main girls of both animes) are voiced by the same seiyuu. In both animes, a boy has a contract with a powerful girl. In both animes it happened big tragedy in the past because of a war between evil and good. In both animes, the two main guys, masters of the girls, have a similar personality. there´s also romance.
In both series the protagonist is a idealistic boy who due to unexpected circumstances forms a contract with a very powerful girl and together they fight and try to understand each other and themselves. Genre of both series is fantasy mixed with a bit of drama, comedy and romace, though Pandora Hearts is somewhat lighter and less depressing while Fate/Stay Night is more touching.
Both have heroic spirits (chains in PH) which fight for the characters
Both have a fairly dark overtone and a sense of impending doom
Both involve magic
Alice has the same seiyuu (voice actress) as Saber from FSN
Both have MC's and their lead support (ie Saber and Alice) have links to a catastrophic event in the past that they are trying to resolve
PH is set in a medieval fantasy world, whereas FSN is set in the modern age
PH centres around the quest to find Alice's memories, whereas FSN is a battle royale