Tulnor Adamance
Tulnor is a fellow professor of graviturgy at the Falador Academy, and Hadha's super smart, super capable, but definitely not as good as he is rival. She is Hadha's long-standing academic equal of over 20 years, and the two have been neck in neck since they were undergrad students. Both actively competing for the same student accolades, the same prestigious graduate advisors, the same jobs, the same promotions. The amount of times they've screwed each other over is countless by this point, though somehow neither one of them has been able to shake the other off completely.
Tulnor comes from a well to do family, encouraged by her father to consider herself better than others. She's intelligent and calculating, and more than willing to take advantage of those around her, but socially graceful enough to do a decent job of pretending otherwise. She strives to cement her place as an acclaimed expert in graviturgy magic, independent of those around her.
With such similar career goals and personalities, the two are destined to butt heads constantly, using their long shared history to get under each other's skin while simultaneously taking advantage of each other's predictability. Perhaps that’s why they keep each other around. The enemy you know is better than the one you don't after all. There is a sense of mutual respect beneath their rather open disdain for each other. It's just buried beneath years of resentment and bad blood.
In terms of current events, Hadha is absolutely convinced that Tulnor is the person responsible for the events that led to his forced sabbatical given their storied history and the fact that she'd have the most to gain from finally being rid of him. Whether or not that turns out to be true remains to be seen.