I have a story outline for how I'd like this story to play out.

Master Chief is a Helghast from Killzone
[img=http://fc04.deviantart.net/fs70/i/2013/016/d/9/beast_marine_by_domls-d5rog1t.jpg]
Samas Aran, the bounty hunter from the Terminus Systems.
[img=http://th00.deviantart.net/fs70/PRE/i/2012/324/7/c/n7_samus_aran_by_kaj18-d5ln8q7.jpg]
The Shepard twins work for the Systems Alliance
[img=http://th02.deviantart.net/fs71/PRE/f/2014/068/c/6/_twin_fates__cover_art_by_dblack930-d79hwoj.png]
Cortana is one of the many AI that work for the UNSC
[img=http://fc04.deviantart.net/fs70/i/2013/121/b/e/cortana_colored_by_oomnine-d5vwvts.jpg]
And possibly the Vault Hunters that reside in the Eden Wastelands
[img=http://fc09.deviantart.net/fs70/f/2014/108/0/7/the_vault_hunters_of_borderlands_1_and_2_by_glench-d6ik4wu.png]
And possibly some ancient reploids from Neo-Arcania (Formally known as Taiwan)
[img=http://fc04.deviantart.net/fs71/i/2012/122/a/b/megaman_vs__zero_by_kofab-d4ydf6a.jpg]