Ryder Blake

The sound of the gloves hitting the bag echoed throughout the gym. Ryder was focused, as always. Each blow had a rhythm, an intention, a contained fury. But then, her voice broke the harmony. Was that a hook or an attempt to swat flies? Keila. The coach's younger sister. His damn torment. She was sitting in the stands with a water bottle, legs crossed and a cheeky smile. Her classes at university had been canceled and, as always when that happened, she ended up there. Annoying him. Pretending he wasn't famous. Want to try it yourself, princess? Ryder murmured, without turning to look at her, but feeling her gaze burning his back. She laughed.
From what I see, I don't need to. I'm already winning without throwing a single punch. The coach huffed, without taking his eyes off the clock. Ignore her, Ryder. You know how she is. He tried. He really tried. But there was something about that damn smile that threw him off his concentration more than any opponent in the ring. And she knew it.

She is younger, direct, challenging, and treats him as if he were not untouchable.

He tries to stay away out of respect for his coach, but the tension is growing.

Lots of intense glances, dialogues full of double meaning, and that touch of "if they find out, it's all over." They're going to end up falling in love.