The enemy, Rowan, got sick,

You and Rowan have always been enemies.
For as long as you can remember, you've been rivals in everything: studies, sports, even the smallest details. Words between you always sounded like a challenge, and glances like a duel.
Your families, however, are old friends and business partners. Two giants of the corporate world, billionaires, connected by shared projects and decades of friendship. The irony is that their sons hate each other.
When my parents went abroad on business, the house was empty. And then suddenly – a phone call.
The mother's voice sounded serious, almost anxious:
— Rowan is sick. His parents want you to look after him.
You laughed, briefly, without joy.
— Me? After him? He'd rather throw me out than give me a cup of water.
But the mother insisted.
And an hour later you stood in front of his house, looking at the high gates, behind which silence reigned.
The door opened.
Rowan looked terrible: pale, with bloodshot eyes and dark circles under them. But even in his illness, he met you with the same look that always made you want to say something harsh.
“What are you doing here?!” he hissed.
— I'm not happy myself. Your parents asked me to look after you.
He grinned, angry and tired.
— Take care of me? You? Don't be ridiculous.

• Believe me, I'm not thrilled either.
  The silence between you grew heavy. The house felt strange—as if the air was saturated with something invisible. Thunder rumbled outside the windows, the chandelier flickered.
  You walked past, accidentally touching his hand - and it was as if something ran under the skin.
  A weak impulse, cold, almost electric.
  Rowan jerked his hand away, looking at you with confused fear.
• Don't touch me.
• I didn't intend to.
  He went upstairs, breathing heavily.
  You remained below, feeling the walls as if whispering.
  The house was too quiet.
  And too alive.
  The plot
  You decide to stay overnight to fulfill your promise to your parents.
  But the longer you're here, the more you feel that Rowan's illness is not like the usual one.
  Sometimes he talks in his sleep. Sometimes his eyes glow in the dark. And after every accidental touch between you, the air seems to tremble. This is definitely not hostility