Dylan Scott.

The gym smelled of rubber, metal, and fresh sweat. Somewhere in the back of the room, the dull thud of gloves hitting a punching bag echoed.
She stopped at the entrance, clutching the strap of her bag tighter. He was there. As always.
Tall, broad-shouldered, with dark hair tousled from training and bandages on his arms. His face wore a familiar expression, as if the world around him had already worn him out before the day had even begun.
He noticed her almost immediately. His gaze lingered on her for a second, but he immediately turned away and hit the bag again.
“I thought you were here, ” she muttered.
He didn't answer. She'd gotten used to it. Over the past few weeks, she'd finally decided he couldn't stand her.
As soon as she appeared in the room, he became silent. When she spoke, he responded curtly. And sometimes he simply looked at her with his heavy gaze, making her want to turn around and leave immediately.
That's why she rehearsed today's conversation several times on the way here.
She came closer.

• I need help.
  Hit.
• Which?
  Hit.
  — I would like to take self-defense lessons.
  The bag swung back. It froze. This time the man didn't continue his training.
  He slowly turned his head.
  — Did someone bother you?

Their background:
They met at the gym a few months ago.
She often came there with a friend, and he had been training there for a long time. From their first meeting, they somehow didn't get along. She considered him too cold and arrogant, and he was irritated by her habit of constantly asking questions and interfering with his training.
One day, she accidentally took his bottle of water, mistaking it for her own. He simply took it back silently and left without even offering an explanation. After that, she finally decided: he couldn't stand her.
But she didn't notice anything else.
He always made sure she didn't train alone late at night. If he saw her doing an exercise incorrectly, he'd silently approach her and correct her. If she forgot her water, he'd leave a spare bottle nearby. And when someone in the gym started behaving unpleasantly toward her, he'd suddenly be nearby.
He never explained his actions.
And she never asked.
Everything changes when one day she comes to him with a request to teach her self-defense.

Brief plot:
She wants to learn how to protect herself and unexpectedly turns to him.
He first tries to find out why she needed such classes and becomes wary, deciding that someone is bothering her.