Nathan Summers is a mutant from the future that is the progeny of Scott Summers/Cyclops and Madelyne Pryor, known to many as Cable.
Cable is the product of an experimental parenting technique. The theory behind this technique is "man, kids are a bother let's send him to the future and let someone else worry about raising him." In his native timeline, Cable's deadbeat dad, Cyclops, produced Cable (real name Nathan Christopher Charles Dayspring Askani'son Summers) with a clone of his presumed dead girlfriend Jean Grey, whose name was Madelyne Pryor. Cyclops proved what a standup guy he was, once again when he left Madelyne. Of course, this happens many years down the road from the present day, and might not happen at all: even moreso than the ins and outs of parenting, the timeline is a fickle thing.
The distant future in which Cable was raised was a Hellish nightmare land in which his clan of warrior mutants battled the ancient evil known as Apocalypse. When Cable was sufficiently grizzled, he grabbed a bunch of technology and traveled back in time to bet on the World Series and make a ton of money. Also he figured he could stop Apocalypse from creating a toxic future.
In this future, he caught a techno-organic virus that made the left side of his body robotic, so if he gets shot in the face he kind of looks like the Terminator and it's awesome.
Cable is all about doing things, not about saying them. He is the telepathic mutant equivalent of a Montana survivalist. He is always prepared for any problem, though most of his solutions involve shooting, stabbing, yelling or saying grizzled action movie one-liners. Though Cable will sometimes inflict his gallows humor upon his comrades, he is pretty much a no-nonsense guy. He wants results no matter what, even if he has to spend his last five dollars on bullets instead of a Whopper Jr. combo meal to attain these results.
Cable practices tough love on his X-Force. He is not shy about calling them stupid or questioning their sexuality. He is from the future, so he knows that the kids are the future, so he is doing it for their own good. He knows that the future is a tough place so he is not going to coddle these kids, he is going to teach them to assemble an AK-47 in a pitch black, freezing room while they smoke filterless cigarettes and listen to 90s industrial metal.
Cable is a thinking man, and is no slouch in the smarts department. But 105 times out of 100, he rushes headlong into a situation with as many guns as he can physically strap to his body. He is remarkably stubborn and always does things his own way. He hates advice and he hates quitters. This oftentimes puts him at odds with Xavier's dream but no one can argue with results. And if Cable gets anything, other than the winning bet at every horse race, it is results.
It is also fair to say that Cable thinks everyone is stupid except for him.
Cable's mutant abilities are telepathy and telekinesis, just like his mom, who was also a clone and a Goblin Queen. There is some amount of speculation that Cable might be a clone, but he is not even remotely a Goblin Queen. Unfortunately, most of his psychic abilities are used to keep his techno organic virus in check.
He can levitate and move objects of about 500 lbs or less for about five or six minutes at a time before it's too taxing. He can communicate telepathically with anyone he can physically see unless they have psychic shielding or other defenses. He can also retrieve small amounts of information from people's mind if they do not have any way of protecting themselves against telepathic invasion. In short, as far as psychics go, Cable is pretty crummy but he is also a disabled veteran so that is an impolite thing to point out.
Cable has a robot arm, leg and eye. He is in awesome shape anyway, but these parts of him make him even better than a human in peak physical shape. His robotic parts are metal and super durable. He can punch four times harder than the toughest, half-nakedest MMA fighter with his robot arm, run as fast as a low level cheetah and jump as high as Shaq wearing the sickest Air Jordans possible. While his robotic parts do not propel him to the level of Captain America, he is significantly tougher, faster and more agile than the average human.
an also use his robotic parts to hack into computers (it is even easier when there is free Wi-Fi around, thank you Starbucks and McDonald's, Cable does not think you are evil corporations, he appreciates you) and override electronic locks. There are limitations to this, of course.
Cable is a man of many skills, so let's start from the top. Cable is an expert with all firearms. Every single one, even the ones from the future that the smartest scientist in 1994 could not even wrap his mind around because they are so awesome. He is just as good with a plasma rifle as he is with a blunderbuss. He is an expert marksman, knife-fighter and street brawler. He could probably take that pony tailed guy from that Highlander show in a sword fight, but maybe just barely because he's not that into swords. He is into all weapons at least a little bit though, and is capable of using environmental objects as weapons, such as vending machines, street signs and domestic animals.
Cable is a sound tactician and leader. He knows how to complete his goals in an efficient manner using the resources at his disposal. He is not opposed to putting himself or others in danger to achieve his goals. He is persistent, dedicated and utterly fearless. He is not as good at tactics as Cyclops or Captain America, but he is good enough to beat most of those Junior High kids who are alarmingly good at chess because they have nothing else to do. Simply put, Cable is the perfect soldier. A Universal Soldier.
Cable is also smart and resourceful. He is always sizing things up and figuring out how to kill or use them. If something does not have a combat-related use, he is not interested in it. If it does have value in a combat situation, he already knows how to exploit it. He is not a genius but he is good at destroying things and killing people for a good cause.
Cable can drive most any aircraft or ground vehicle somewhat proficiently. He is pretty good with computers but not a total nerd about it.
Cable has a floating house/spaceship from the future called Greymalkin. It is basically where he sleeps when he wants to get away from Kane and Domino nagging him, and where he keeps half of a Domino's pizza and a can of Rainier in the fridge. Greymalkin enables Cable to "bodyslide," or teleport, at different times. Its resources are limited so Cable does not use this ability a lot these days, but he can teleport in dire situations of he remains in contact with Greymalkin. Greymalkin is basically just a floating house, but could presumably shoot lasers at an asteroid if needed.
Cable has tons of guns. From the future. They can shoot rockets, plasma, lasers or any number of other things. He chooses different guns for different situations. He also has access to environmental survival gear, jetpacks, giant shoulder pads, utility belts, grappling hooks, spacesuits and anything else that might sell a Batman action figure to an eight year old. He also has a Montana-style stockpile of modern weaponry.
Cable is the leader of X-Force and an ally to the X-Men. As such he can sleep in the mansion and gets paid minimum wage for teaching classes. His X-Force will basically do anything he asks. The X-Men will also help him out if he needs it, which he doesn't.
Cable can also travel through time, though it is hardly a fun thing to do and there's a lot of work to be done in the present, so it is not an ability that he abuses. This also gives him knowledge of the present and future, and as such if he ever needs money he can really just bet on a horse race or invest in a NASCAR driver or design an iPhone app that no one has ever thought of, oops, time paradox.
Cable is extremely paranoid and hard to get along with. He comes from a terrible war-torn future and has a hard time showing outright mercy or compassion, though he has a good heart. He does not empathize with crybabies or weaklings, which describes 50 of the X-Men. He has dark visions about the future all the time and can just be a bummer to be around. He never has anything nice to say.
Cable's future family is all dead so he has a hard time getting close to people. He does not really trust anyone that is not named Cable. He is extremely stubborn and extremely militant, which almost always puts him at odds with the left-wing, peacenik terrorist unit known as the X-Men. They appreciate each other, but often do not agree. Cable does not back down, which is frustrating for everyone. He might do it your way if you can beat him at arm wrestling, but how realistic is that?
Cable is infected with techno organic virus. If not kept in check by his psychic powers, it will quickly overwhelm and kill him. This is a constant worry and requires constant effort on his part to contain and monitor. It is like the worst form of future cancer and he's always doing his own radiation therapy.
Cable is also fated to be the man that kills Apocalypse, which is a burden by anyone's definition of the word burden. Mostly, he is a stubborn, militant a-hole that is full of paranoia problems and trust issues. Imagine Bill O'Reilly with a pulse cannon and a cyber eye and just think about how hard that would be to deal with. Needless to say, he has a hard time finding solutions that do not involve shooting or punching. Not every problem requires those solutions, so sometimes he is a fish out of water.
Cable also has problems going through metal detectors.