INTEL.
RESIDENCE
Noble Street, Patonce House, Upper Cove.
APPEARANCE
Squall is the first of the Final Fantasy characters to be "Nomuraified". What that means is that he's got feminine features (admittedly not as bad as X's protagonist Tidus), wears leather, and walks around with one too many belts.
He's got a scar on his forehead that goes from his forehead to his nose, blue-grey (they're described as blue but they seem more of a combo to me) eyes, and shiny brunet hair that frames his face. Squall stands at 5'8" and can normally be seen wearing his trademark necklace, Griever.
Much like Cloud he wears earrings; I am still unsure why.
PERSONALITY
Silent and introspective, Squall's the type of person you'll almost always find lost in his thoughts. He doesn't like responding to much of anything except for challenges, often thinking he either has to prove something or just protecting his pride. He doesn't communicate well with other people, often allowing them to talk until they decide to stop. While this makes him a very good listener, he never seems to generally care about conversations that go on around him.
He can be cold and dismissive, although this is only because he tries to take a realist as well as fatalist's point of view. Squall strives to be independent both physically and emotionally; he blocks out other people and forces mental barricades around himself to ensure he never feels anything for them. This stems from his early childhood where he acquired an abandonment complex (leading to his fatalistic mentality). He has such high barriers around himself that he mentally rejects the idea of companionship, believing it to make people weak.
All the same, Squall is someone that is fiercely loyal. To most people, he can be seen as a leader because he is able to look at things calmly and rationally. Unfortunately these traits, coupled with his strength of character, usually lead people to depend on him for his reliability.
Squall is obedient in the face of orders and commands, something that comes from his training as a SeeD. When given orders he prefers not to think excessively, instead just follow through with the task he's present with.
HISTORY
It is widely believed that Laguna Loire is Squall's father, this is very heavily implied in the game. I am going with this for canon.
Squall Leonhart was born to Raine Loire in Winhill village (at this time Laguna was in Esther, he had recently sent back Ellone to Raine and intended to follow behind her in the future), however due to complications at birth Raine died. Squall and Ellone were sent to live at Edea's Orphanage where they, for a time, grew up together with a number of other children.
Eventually, thirteen years before the game's beginning, a sorceress came to the village looking to pass on her powers. Edea took them into herself and managed to encounter the future Squall that had, somehow, managed to travel into the past. Squall told her of SeeD as well as the sorceress she had just taken the powers of just before he was sent back into the void of time. Sometime after this incident Ellone was sent on the White SeeD ship for her own protection. Squall, who had taken to Ellone the most, spent the rest of his time at the orphanage waiting for Ellone to return. Eventually only he and Seifer remained; the two were sent to Balamb Garden to be trained as SeeDs.
In time both Seifer and Squall forgot their shared past due to the use of their GFs (Guardian Forces), instead focusing on their training. Things remained this way until ten years went by and Squall became a SeeD. He, together with Zell Dincht and Selphie Tilmitt, were sent on a mission to assist the Forest Owls of Timber. There they aided the leader, Rinoa Heartilly, in trying to win Timber's independence. This objective was postponed when Seifer (Rinoa's sort-of boyfriend at the time) broke out of the Garden and attempted to assassinate the President of Galbadia (nation ruling Timber) and failed. Squall, together with his party up to this point and Quistis Trepe, escaped onto the last remaining train and headed to Galbadia Garden.
Once there they found out that Seifer had been executed for his actions and held responsible for the entire situation in Timber. The party, although saddened, had little time to recover and were sent on another mission:
To assassinate Sorceress Edea.
Together with their new comrade, Irvine Kinneas, the party tried to carry out their new orders. This too ended in failure, resulting in the entire party being thrown into prison. Naturally they escaped (through the aid of the then-released Rinoa and Irvine) only to discover that missiles were being fired at both Balamb and Trabia Gardens. Selphie and two others headed to Galbadia's missile base to stop the launch. They stop the missiles and activate the self-destruct mode; unfortunately one of the soldiers that remained in the building reactivates the missiles. As the base explodes, Selphie and her group are trapped in the blast.
Meanwhile Squall returned to Balamb Garden to warn them of the missiles. However, upon arriving, Squall finds that the school has been divided into two factions: Headmaster Cid's and Gardenmaster Norg's. Too confused to take a side, Squall rushes into the garden; he decides to take Cid's side and eventually tracks him down. Once he does, he gives his report to Cid about the missiles. Squall carries out Cid's plan to activate the unused underground shelter that the garden was built on.
Narrowly, Squall is successful and the garden becomes mobile.
For several days the Garden drifts through the ocean until it runs into Fisherman's Horizon. The technicians there offer to fix the Garden, but before permission can be acquired Galbadian soldiers enter the city looking for Ellone. The Mayor attempts to reason with them, fails, and Squall + two jump in to defend him. Directly after this Selphie and her two party members return to the Garden (they had escaped the explosion by hiding inside one of Galbadia's mobile weapons).
Later on, Selphie holds her Garden Festical at Fisherman's Horizon. Almost right after the event Balamb Garden heads to Balamb, wanting to ensure its safety from the Galbadian army. As it turns out, the army has taken over Balamb. The town is liberated, although the enemy turns out to be two SeeD cadets that had sided with Seifer Almasy (by this time he had become the Sorceress' Knight, he was acting as her commander in the army).
At Balamb's liberation, Selphie suggests they head to Trabia Garden. Squall agrees and they go. As expected the Garden is in shambles (it was hit with the missiles), but an important part of the story comes up here:
Irvine reminds everyone (Selphie, Squall, Quistis, and Zell) that, once upon a time, they had all lived together in Edea's Orphanage. Remembering their foe as their beloved Matron and shared history, the SeeDs (plus Rinoa) wish to visit the old Orphanage. Along the path they encounter the now-mobile Galbadia Garden, the two gardens clash and Squall is killed during the battle.
ABILITIES & STRENGTHS
As a fighter, Squall is likely near the top of his class. He's proficient in battle tactics, fighting (armed and hand-to-hand, prefers armed), and can think on his feet whenever necessary. Squall is able to listen to another person's command and knows how to take orders in addition to following through with them.
He is intelligent enough to make decisions in difficult situations, maintain his composure, and rationally think things through before taking action. As an ally, Squall is extremely reliable.
All of Squall's abilities revolve around his gunblade (the gunblade does not shoot actual bullets, the trigger just sends a heavy vibration through the blade).
WEAKNESSES
Just as Squall's greatest strength is his mind, it's also his greatest weakness. Squall can be too introverted and contemplative, to the point of never voicing his opinions or emotions on topics. His thoughts usually have to be forced out of him by others to appear and normally they are very condensed versions of his original beliefs.
In the ways of battle, Squall can be considered "new" and that might be seen as a weakness. It's true that he's been training since his youth for battle and striving to be the best, but until he became a SeeD he had no real combat experience outside the Garden's training facilities.