The birth of Elis Rosier was nothing short of a un-regrettable mistake on Sharon's part. In her defense, Oh Youngchae was a charming man with dashing looks and a way with words. Sharon, who believed she had every right to find other men to entertain her when her husband failed to, found Oh Youngchae, a Korean immigrant, in his new store in Diagon Alley. He came from a family of Korean pure bloods and was amazing with potions, and Sharon found that as a good enough fling that may have lasted a little longer then she meant for it to be.
Sharon, who had been married into the pure blood family of the Rosiers' by her parents on the insistence that she provide pure blood offspring, had never truly experienced love the way it was supposed to be experienced; so when she met Youngchae, she became addicted to this feeling of happiness that she couldn't seem to get with anyone else. At the time when she had gotten pregnant with Youngchae's child, she hadn't been aware he was pure blood, so as one does, she freaked out and cut off all contact with him, trying to figure out what to do.
Knowing she didn't have the strength nor the desire to abort the child, she decided to keep it and lied to her husband, Jonah, telling him it was his child. Even then, her heart ached to run to Youngchae who she knew would've comforted her in this moment. Oh, how stupid she'd been to run from love. As ironic as it was, her illegitimate child was born on Youngchae and Sharon's anniversary. It's safe to say that she was miserable on November 14th for a number of reasons, not just because she was exhausted and had just given birth.
Elis grew up starved of love. Naturally, that would make one a very peculiar child right off the bat. His mother barely regarded him because just his existence made her think about her potential love and what she'd lost, and his father didn't see the need in attempting to raise a child that clearly didn't belong to him despite what his wife said. At some point during his life, instead of completely disregarding him, his parents did a complete 180 and made him the center of an obsessive attitude to make him perfect as a result of their marriage beginning to fall apart.
When he was seven, his first sign of magic showed as a result of the sudden stress his parents had put on him. His mother, for some particular reason, had enrolled him in gymnastics and demanded he be the best of the best. She had him practicing whenever possible and although he hated his mother's pressuring, he enjoyed the activity itself so he continued to push through. His father seemed to be grooming him to be a businessman, something Elis was anything but interested in. He'd hammer bad lessons in young Elis' head until he couldn't take it anymore and simply broke. As a result of this extreme pressure, he exploded a nearby stack of paper in flames.
Jonah had believed that he had done it on purpose, despite the fact that Elis wasn't even aware he could do that, and punished him sorely. From there it only escalated. Both Sharon and Jonah harbored particularly controversial views, although Sharon, as expected, seemed to be the more lenient of the two since she never really had the heart to punish or completely chastise the result of her and Youngchae's love. Jonah didn't tolerate a divergence from his views and constantly put toxic messages in Elis' mind.
Maybe, at the beginning of Elis' first year, he would've completely believed them, but as he developed his own ability to apply critical thinking, he slowly dug himself out of the grave Jonah had been trying to put him in since the boy had been born. It didn't matter because soon his parents turned to his grades and social skills and found ways to turn his outstanding grades into negative things. They'd claim he hadn't been working hard enough and that he needed to better, which eventually resulted in his low self-confidence, anxiety disorder, and severe panic attacks, as well as his immense fear of his parents; so strong that they had become his boggart.