Gabriel's origins remain unknown. Some have argued him being named Gabriel is no coincidence and hints towards a darker destiny the order knew about.
This is indirectly proven in Mirror of Fate when the elders of the brotherhood and Pan showed Marie Gabriel's fate in a shard of the titular mirror.
It's been rumored that he was an abandoned child of the Cronqvist Family (differ from the original Cronqvist), hinting at his eventual fate to become Dracula.
The game developers stated that Gabriel chose the name Belmont due to his love for mountains, since Belmont connects to them. In fact, "Belmont means "Beautiful Mountain" in old French.
Gabriel's appearance is the result of input from Hideo Kojima. Kojima felt the main character needed to look more "heroic" than his original design implied. Kojima Productions also advised the team on facial animations and character design in general.
The original intent for Lords of Shadow was to be a reboot of the Castlevania franchise with Simon Belmont as the protagonist. Footage of this intended game can be seen here. Eventually Mercurysteam was given free reign to write a new story, and decided to tell the origin of Dracula, and invented Gabriel.
Gabriel's name is stated to have come from the Archangel Gabriel, a prominent angel found in the New Testament famous for announcing the births of Jesus Christ and his cousin, St. John the Baptist. The name translates to mean "Strength/Man of God". It also means literally "The Voice of God".
The word "Dracul" literally means "Dragon", which is sometimes a synonym to the term "Devil" due to the Biblical reference.
Dracul is also the title of Vlad II, the father of Vlad III Drăculea.
Gabriel has many traits and characteristics in common with the Dracula of the classic Castlevania games.
Both were once great warriors before the woman they loved died. This caused both of them to spiral into darkness.
Both abandoned their original names after becoming vampires.
They have similar powers, including the control of legions of monsters, command of a dark castle, and the ability to transform and summon fireballs.
Both still held a measure of love for their respective versions of Alucard, in spite of their latter enmity.
Both develop distainful attitudes toward humanity and become adversaries of God, dedicating themselves to spiting Him.
Both are shown to drink blood from goblets, and to throw the goblet away before encountering enemies.
Both also use similar lines in combat, i.e. "What is a man, but a miserable pile of secrets?"
Both are able to return from the dead.
Unlike Dracula, Gabriel is playable in every game he has appeared in, and is playable as often as he is fought.
Also unlike Dracula, Gabriel has to date only been defeated twice, once against Zobek, and once against Alucard and Simon.
He also has been nearly killed by two lightning users, Laura and Nergal.
Gabriel's origins and motivations are said to be majorly inspired by the 1992 film Bram Stoker's Dracula starring Gary Oldman. This film also inspired the backstory for Mathias Cronqvist in Lament of Innocence.
Gabriel also parallels both Mathias Cronqvist and Leon Belmont from Lament of Innocence, as both the progenitor of the Belmont line and the source of their eternal conflict.
Gabriel's quest parallels other protagonists from the classic Castlevania series, most notably Leon and Richter Belmont, as both began their quests to rescue the women they loved. In Gabriel's case, although he was able to rescue her, she was not returned to him.
He also parallels Simon Belmont, in that he embarked on a quest to destroy a powerful curse. In Simon's case it was cast on himself, while Gabriel sought to save the world and Marie.
Gabriel also parallels his greatest enemy Satan;
Both started as the greatest of their kind but fell to become the enemies of all things good.
Both are masters of combat and magic.
Both are masters of their own realm (Bernhard Castle for Dracula and Hell for Satan).
Most notably, both are named "The Prince of Darkness".
In the Book of Revelation, Satan is also called "The Dragon".
Both were challenged by the greatest warrior of the Brotherhood at the time, and fought him by countering the others' magic.
Before his fight with the Forgotten One, Gabriel says the classic line from Symphony of the Night: "Enough talk...! Have at you!"
It should be interesting to note that Gabriel does not refer to himself as Dracula (which means Son of the Dragon in Romanian), but Dracul, the Dragon. Vlad III, aka Vlad Țepeș (on which the literary Dracula is based), was the son of Vlad II Dracul, who in turn was named as such for his affiliation with the knighthood know as the Order of the Dragon. In the Resurrection DLC, Gabriel begins comparing himself to a dragon, which could be the origin of the name, and in Lords of Shadow 2 he turns into a ghostly dragon. However, it has been confirmed that Gabriel is indeed the Dracula of the Lords of Shadow Timeline.
Interestingly, although Gabriel calls himself "the Dragon" in Romanian at the end of Lords of Shadow he never actually names himself. He only refuses to take his old name.
Gabriel defeated Satan by countering the fallen angel's magic with its opposite, i.e. light with shadow and vice versa. Years later, Gabriel's own son would fight his father in the same way.
Before the battle with the Golden Paladin, Gabriel uttered another classic line from the Castlevania series: "What is a man... But a miserable pile of secrets!"
Like the Dracula from the original series, Gabriel is able to shoot a wave of fireballs at his enemies.
Dracula makes the same offer to Alucard in Mirror of Fate from Symphony of the Night, "Join me in remaking this world!"
Even though Dracula now controls Bernhard Castle, his rule seems to be contested by enemies, as seen in the case of the witches who released the Daemon Lord and the Toy Maker who resurrected him, and several monsters seen in trailers for Lords of Shadow 2.
Ironically, the battle between Trevor and Dracula mirrors the one between Gabriel and his greatest enemy, Satan, with each countering the others' magic with it's opposite.
This increases the parallels between Dracula and Satan.
In the first trailer for Lords of Shadow 2, Gabriel takes the appearance of a dragon. It is a reference to the names Dracul and Dracula, but also to the original Dracula's second (and sometimes third) forms.
In this same trailer, it shows that Dracula has no reflection. This does not stop him from seeing visions in the Mirror of Fate.