Gosh you’re so kind to me, thank you! Q_Q I’m so honoured and grateful to have your praise!
Gabriel’s family name is Renard! The implication is that he’s a distant relative of the Renard family from the games. His backstory is revealed a bit in chapter 34.
To summarize - Gabriel’s father has a business in raising and selling horses. The Belmonts were one of their clients when Simon was a child (he and Gabriel were both around twelve at the time). Gabriel was apprenticing under his father and met Simon when they sold the Belmonts their horses (Simon’s included, may she rest in peace.)
But it wasn’t just a transactional handoff - the Renards stayed on the estate for a few weeks to teach the Belmonts how to best establish the stables and tend to the horses they were sold.
And Simon, being a lonely child with no siblings nor parents, asked Laurent if Gabriel might be able to stay a bit longer.
Hilariously, Gabriel never wound up leaving, lol, and has taken residence in the Belmont hold with Laurent ever since.
Gabriel is also proficient in combat, and Laurent seized the opportunity for him to train alongside Simon as a sparring partner of similar stature (being around the same age), so it worked out well!
Gabriel’s family is still alive and the implication is that he leaves the Belmont estate to visit them when he can. I haven’t given too much thought to whether or not he has siblings, though.
He’s single - I have some ideas about a significant other for him, but it won’t be explored directly in TRFSB. In one version of the story, I considered pairing him off with Selena’s sister Sofia. But I feel like they're better suited to be acquaintances - they’re both light-hearted teasers with good humour. :) Good folks all around. I wish I had them interact more apart from the sending-off banquet in chapter 26 lol!
I completely agree with you that Gabriel is a pillar for a lot of the mental foundation for the family. He has stepped in to diffuse Laurent, and Laurent has leaned on him over these years, too. Gabriel has helped Simon protect the estate, brought him and Selena together when they couldn’t see the signs themselves. He’s also a great uncle-figure and example for Mathieu. They’d be so lost without him!
I really, really like Gabriel as a character. He’s like the glue that keeps everyone together. And I’m so happy you see him that way, too! ^_^