It's the hood
It's amazing how young children can so quickly and easily forget wrongs that have been done against themselves, given the right environment and nurturing. The tears can suddenly stop and friendships instantly restored, bumps and bruises kissed away.
Shannon is the fiery one who screams and shouts when Nigel grabs a toy which he owns. But Shannon has learnt how to deal with this and related disappointments by quickly dropping the toy (to avoid confrontation and physical injury) and diverting her attention to another toy (to avoid personal disappointment). Nigel has learnt to take another toy as an exchange gift in order to increase the chances of acceptance and lower the risk of a conflict.