For those of you who follow me on Twitter you might recall that a while back I asked the question of what sort of adversary Sam should have if she were ever to get a spin-off, be it a game or comic series with the requirements being that they would have to be big enough to be a threat but small enough that they wouldn't detract from Sam's character or personal growth and that they had to reflect Sam's internal conflict/demons in some way.
After going through my library of games, movies, novels, comics and TV shows I think I found the kind of villain I would want Sam to go up against. Rafe Adler from Uncharted 4 A Theif's End. Now at this point this is just the early stages of the character, I just got this idea so we're using Rafe as more of a template for the eventual villain who would have different backstory and goals but the basic character is the same.
In U4 Rafe is a self-centered, man child who only ever thinks about himself and seeks to make a name for himself as he doesn't want to be known as the man who got rich on his parents wealth. He is impossible to put up with and even a people person like Sully or Nate can barely stand to be around him for more then a few seconds before they've had their full of him. Even his allies can barely tolerate him as shown with Nadine as she is just as fed up with Rafe as she is the Drake brothers, who are killing most of her men throughout the game while her annoyance at Rafe is more due to his constantly bitching about everything from the Drake brothers to Nadine's mercs to Nadine herself. He also has a bad habit of turning on his own allies and will hurt of kill them just because they annoy him.
In other words, the exact opposite of Sam. Sam is one of the nicest, funniest and most loyal people in the Tomb Raider series. While she can and has gotten angry at Lara it's so rare that the few times it happens that Lara and Jonah actually comment on it and while part of it is down to Himiko trying to take over Sam she still remains loyal to Lara as revealed in Choice and Sacrifice when it was revealed that she would often talk about Lara in a positive way and was even willing to kill herself if it meant protecting Lara. Sam is even willing to put up with people who annoy her like Whitman who, much like Rafe, had a tendency to why about everything that annoyed him and had a sense of self importance that would actually dwarf Lord Voldemort's. Sam despite his constant tantrums, which apparently happened a lot, Sam continued to be nothing but professional with him even though she suspected, correctly, that Whitman was planning to steal the credit for finding Yamatai away from Lara which is why Sam made sure to record all of Lara's hard work so she would get the credit she deserved. And throughout the entire series, despite likely developing a inferiority complex, despite feeling that Lara does see her as her equal anymore and despite being someone who loves drawing attention to herself Sam never tries to take credit from Lara for any of her findings.
Please note that the reason Lara was even looking for Yamatai in the first place was because Sam had told her the story her grandmother told her when she was young and yet while filming the voyage to Yamatai, as stated before, Sam made sure that Lara would get the credit for everything she did while Sam was content to remain behind the camera for the whole journey. And this didn't change in the comics as while Sam was pretty much the Deuteragonist of the story she never tried to take attention from Lara and always supported her no matter what.
Both Sam and Rafe were born into wealth but whereas Rafe only cares about himself and will hurt anyone and everyone to get his way, which includes the people who are on his side and as a result alienate everyone from helping him, Sam is cares deeply for those close to her and is due to being a social butterfly is quick to make friends who will be there for her when she needs him, even if it takes them a while to get there.
So Rafe is really the perfect adversary for Sam as he can help show Sam's better traits by seeing her go up against someone who embodies everything she stands against. Selfishness, needless cruelty and pettiness all of which Sam has shown open contempt for with Whitman, Mathias and Himiko once she learned her true nature.
So that's my idea for what sort of adversary Sam should go up against should she ever get a spin-off game. Also as I posted on Twitter, as a Shout-Out to Uncharted 4 and Sam's main voice actor Arden Cho's character Kira from Teen Wolf, the finally boss fight for said game should have both Sam and the villain having a Katana sword fight just cause.