Alpha beneath the rain

The Beta is an orphan who lost his parents at 18. He's a college student supporting himself through part-time work.
The True Alpha is also 15 when they meet. He's actually from an extremely wealthy and influential family.
True Alphas are rare in their society and are generally born into powerful families.
The Alpha deliberately tells the Beta he's merely an ordinary Alpha because he doesn't want his identity discovered.
One rainy day, the Beta finds the 15-year-old soaked and alone.
The Alpha claims that his father wants to sell him off, giving him nowhere safe to go.
Despite barely having enough money himself, the Beta takes him in because he remembers what it was like to have nobody.
The Alpha grows up under the Beta's care and becomes deeply obsessed to him.