My list is incomplete, Fallout, Elder Scrolls, Soul Calibur, Loaded, The Darkness, Legend of Zelda, Lollipop Chainsaw and a few others are missing but I will add them at some point. The list will be longer soon enough, a few have some form of plot that may need a work around. The first six games is something I really want to though I welcome the rest of them as well.

Bold = Me

[b][u]Mortal Kombat: [/u][/b]

-Sindel x Kitana
-[b]Kitana[/b] x OC (or MK character)
-[b]Mileena[/b] x OC (or MK character)
-[b]Mileena[/b] x Kitana
-[b]Reptile x MK
-Sonya Blade x Jaxx	
-Good MK Character x Bad MK Character
-Good MK Character x Good MK Character
-Bad MK Character x Bad MK Character
-MK Character x MK Character
-[b]Sub-Zero (or Cyber Sub Zero)[/b] x Scorpion (or Noob Saibot) 
-OC x OC

[b][u]Timesplitters: [/u][/b]

-[b]Jo-Beth Casey[/b] x Sgt Cortez 
-Gretel x R-108 (or 109/110)
-Corp Hart x Sgt Cortez
-Viola x OC (or TS character)
-Chastity x OC (or Ghost or TS character)
-Iisa Nadir x TS Character (or OC) 
-OC x OC
-TS Character x TS Character

(Possibility of doing a TS2 thing were we change upon the time period we are in)

[b][u]Perfect Dark: [/u][/b]

-[b]Joanna Dark[/b] x Velvet Dark
-[b]Joanna Dark[/b] x Jack Dark
-[b]Joanna Dark[/b] x Elvis (Maian)
-[b]Joanna Dark[/b] x OC
-DP Character x DP Character
-OC x OC

[b][u]Bioshock-1, 2 and Infinite: [/u][/b]

-[b]Elizabeth[/b] x Booker
-Elizabeth x Elizabeth
-Splicer x Splicer
-Big Daddy x Big Sister
-[b]Elizabeth[/b] x Jack
-[b]Eleanor[/b] x OC
-Eleanor X Elizabeth
-OC x OC

[b][u]Borderlands: [/u][/b]

-[b]Tiny Tina[/b] x Vault Hunter
-[b]Tiny Tina[/b] x OC
-[b]Tiny Tina[/b] x Roland 
-Lilith x Maya
-Vault Hunter x Vault Hunter (Singles)
-Vault Hunters x Vault Hunters (Doubles)
-OC x OC

[b][u]F-Zero+Cross Over: [/u][/b]

-Captain Falcon x Jody Summers
-Captain Falcon x OC
-F-Zero Character x F-Zero Character
-Captain Falcon x Samus
-OC x OC

(These ideas will be based around the style of GTA/Saints Row 1 and 2
The Cross over will be a Metroid x F-Zero like RP)

[b][u]Left 4 Dead: [/u][/b]

-Survivor x Survivor
-[b]Witch[/b] x Survivor
-[b]Witch[/b] x Special Infected
-Survivor x Special Infected
-OC x OC

[b][u]Hunted: [/u][/b]

-Caddoc x E’lara
-Caddoc x OC
-E’lara x OC
-OC x OC

[u][b]Golden Sun: [/u][/b]

-Issac x GS Character
-Felix x GS Character
-OC x OC

[b][u]Star Fox: [/u][/b]

-Fox x Krystal 
-Fox x Falcon
-Fox x Wolf
-[b]Wolf[/b] x Krystal
-SF Character x SF Character

[b][u]Street Fighter: [/u][/b]

-[b]Poison[/b] x Ryu
-[b]Poison[/b] x Ken
-Chun Lee x Ryu (or Ken)
-Poison x Chun Lee (or another Female)
-SF Character x SF Character
-OC x OC

More to come.