The Heartless Servant and The Untouchable Prince.

Jaew works in a mountain park and guides tourists. But later Jaew's grandmother who is the nanny of a very rich family who Jaew have never met, fell down the stair and broke her leg. When Jaew visits her grandmother in the hospital in Bangkok her Granny is worried sick over her Khun Noo (that's what Jaew grandmother calls him) and ask Jaew to take care of him until she gets better. She takes a taxi to the family, On the way they make a stop to try to find their way and is almost run over by a careless motorbike driver and fall down. The driver gets hurt and Jaew gets furious. She lends the Taxi and follow the careless driver and discover that he is going to the same address she is, she follows him all the way into the house and the "fight" begins. So that's how Khun Chai met.