I wrote some fic for your enjoyment (I do love Merchant of Venice). That being said, this here isn't quite traditional slash; the pairing is by no means the only focus.
Summary: Shylock knows himself only as angry and bitter, so it shocks him when he performs an impulsive act of mercy. Antonio knows he can rely on his friends, so it shocks him when he has to rely on his enemy instead. Post-play.