The biggest lovebirds

Torch, despite coming off as brutish, is quite scholarly. Not many dragons seek knowledge like he does, and those dragons who are uneducated bore and irritate him. He learned very early on that most dragons don't make for good conversationalists and won't show any initiative, instead waiting for the Dragon Lord to bark orders or dismiss them. He also learned at a young age that a significant majority of his subjects aren't all that concerned about promoting the general welfare of their kind. This disillusioned Torch and caused him to dismiss his subjects quickly; making decisions not so much with their consent but more for their own good, growing more peremptory over time. Strangely, dragons seem to like it that way. Torch, however, was starved for good company.

Blaze is a dainty dragoness who likes chasing storms for the thrill of it. She is also very interested in the stars and what might be beyond them. When she was younger she gained a reputation as an airhead that she never quite got rid of. Her peers were relentless against dragons as physically weak as her and her best defense against them was becoming the object of the stronger males' favor. This meant feigning admiration and acting exceedingly stupid to prop them up. The truth is that she is very intelligent.

One day Blaze went to Torch's cave to deliver a slab to him on behalf of her father. Torch was initially annoyed that Blaze's father had decided to send another dragon in his place without permission, but he was too busy to make an issue out of it. He told her to leave it in the pile and dismissed her, without even facing her.
When Torch didn't hear Blaze leave, he turned around and saw that his mathematical notes had caught her attention. Under normal circumstances he'd have hollered at her to get out, but her fascination with his work made him pause. He approached her and asked her what she knew about geometry.

Blaze said, "nothing yet."

Blaze's decision to add "yet" to her response intrigued Torch and he offered to teach her about it if she was serious about learning. Upon noticing how uncomfortable Blaze was to be alone with him, he offered to continue their conversation in a more public area. Blaze took note of his attentiveness and how that empathetic quality took nothing away from his authority.

Torch began to give Blaze lessons and she began trusting him. Her visits gradually became longer and eventually she started having philosophical conversations with Torch, who was thrilled to finally have a companion who didn't exasperate him with their lack of intelligence. Since the passing of his adoptive father, Torch had almost completely given up on trying to engage academically with other dragons.

Over time, the two grew comfortable around each other. They both started sprinkling personal experiences into their conversations and were surprised at how much they had in common. They shared a lot of moral common ground, shared a similar sense of humor, and had strained relationships with their biological parents, if for different reasons.
They anticipated seeing each other with excitement.

Blaze was starting to feel attracted, whereas Torch had firmly pushed that idea out of his head as soon as he saw the young and beautiful dragoness. He deemed her out of his league, accepted that as fact and moved on. Because Torch had already put himself in the mindset that nothing would happen between them, he was obtuse when Blaze started dropping hints that she liked him. When Torch finally understood what was happening, he sufficiently embarrassed himself. Fortunately for him that just endeared him to Blaze. What sealed the deal for her was not only his desire to be a dedicated father, but also his treatment of her after she lost her hearing. For Torch it was Blaze's non-judgmental, gentle validation where other dragons would have mocked him for his sensitivities.

Despite being married for over half a century by the time Ember assumed the throne, they are still very much in love and, much to Ember's chargin, openly affectionate.
In truth, Ember isn't too bothered by her parents' apparent fondness for each other. She's happy they get along. She just... doesn't need to know, okay?