noun
twain
TWAYN/twˈeɪn/
Two people or things considered as a pair
The twain of pears rests together in a shallow bowl.

Etymology
Old English twegen meant “two” in the masculine gender. After English lost that gender distinction, twain survived as an alternative to two, allowing it to name two people or things considered together.
In context
I'm going to let out the pigs alex's going to let out the cows and hopefully never the twain shall meet