The secret to a successful twist is that it should straddle the line between surprising and plausible.
Sweeping the leg from under the player with an out-of-the-blue reveal only serves to weaken any narrative and crumble any decent character development, so it's vital to deceive the player into thinking one way, only to flip the script and have it make even more sense once the twist has been revealed.
The gaming medium is so centred around heroes and villains, and often developers will use the tried-and-tested trope of 'good guy turns bad' to deliver a surprise that nobody saw coming.
In theory, this should always, at the very least, conjure a shocking narrative turn of events that throws the game's story into chaos, for better or worse. However, the shroud of goodness that a character envelops themselves in often does not hide who they truly are.
Sometimes, it's painfully obvious that an ally is soon to reveal themselves as an antagonist. All suspicion quickly turns into anticipation of when --rather than if-- that reveal will take place.
It doesn't take an eagle's eye or a sniffer dog's nose to figure out that these characters are far from the good guy they claim to be.
10. Harry Flynn - Uncharted 2
Anyone with that clear of a British accent in a sea of American voices is surely worthy of suspicion
Making his introduction to the player in the opening chapter of Uncharted 2: Among Thieves, Harry Flynn is presented as one of Nate's past acquaintances. Sporting a slicked back hair do and smarmy, smug smile, Harry's slippery personality felt fitting of a man who would befriend --and eventually betray-- a treasure hunter and notorious history thief.
It doesn't take long for Flynn to turn on Nate and co, as he slinks away during a heist in Istanbul after acquiring the next clue on the trail to discovering Marco Polo's Lost Fleet. Drake spends the next three months in a Turkish jail cell (with its own bucket, no less) and Harry returns to his post as antagonist Zoran Lazarevic's lap dog.
A British accent spoken from a character model that looks as shifty as Nate is handsome is surely cause for concern. From the moment we meet him at the beach-side bar, it's hard to imagine him as a dashing video game hero.
Harry Flynn's betrayal of Nathan Drake was never a case of if it would happen, rather when.