In "Eveline," what did the children worry about most while playing in the field?

In the story, Eveline and her siblings used to play with other children in the field, but her father created a constant sense of fear:

Her father used often to hunt them in out of the field with his blackthorn stick.

In other words, it was the fear of their father's violence which bothered them during their play. It was as though he cast a shadow over their lives, one characterized by violence and cruelty. 

Despite these fears, Eveline remembers that they were still "happy" when they played. Her father's aggression, however, would continue throughout her life, particularly after the death of her mother. 

This worry is important in the story, not only because it helps to characterize her father, but because it gives an insight into Eveline's desire to escape. Sadly, however, Eveline will never escape her life in Ireland. It is as though her father's shadow has never left her.