This 2014 bird study showed the complementary effects of neurochemicals vasopressin and oxytocin in the hypothalamus.

Oxytocin neurons in the hypothalamus promote pair bonding and gregariousness in females.

Vasopressin neurons in the hypothalamus promote maternal care, social recognition, and gregariousness in both males and females, and aggression in males toward females.

Vasopressin and oxytocin released generally and in other parts of the brain have different effects. For example:

“Central administration of oxytocin also attenuates stress-induced effects on the brain and reverses stress-induced social avoidance.”

http://www.pnas.org/content/111/16/6069.full “Hypothalamic oxytocin and vasopressin neurons exert sex-specific effects on pair bonding, gregariousness, and aggression in finches”