[Charles] asked his mother [Lena] to read to him. [Lena] was too busy. [Chris] and his brother [Charles] were rarely seen apart. [Theodore] took his brother [Chris] to Las Vegas to go gambling.
('Theodore', 'Lena')
[Theodore] took his brother [Chris] to Las Vegas to go gambling. [Chris] and his brother [Charles] were rarely seen apart. [Charles] asked his mother [Lena] to read to him. [Lena] was too busy.
[{('Theodore', 'mother', 'Lena'): [('Theodore', 'brother', 'Chris'), ('Chris', 'mother', 'Lena')]}, {('Chris', 'mother', 'Lena'): [('Chris', 'brother', 'Charles'), ('Charles', 'mother', 'Lena')]}]
['brother', 'brother', 'mother']