“It doesn’t seem fair that he just switched sides whenever he wanted,” squawked Crow.
“No, not fair at all,” growled Bear, “Bat has wings but he did not stay with the birds.”
“And he has teeth but did not always help the mammals,” added Crow.
All of the animals nodded and looked at Bat, “Because you could not choose your friends during war, you will not have them during peace. From this point forward, you will only fly at night when everyone else is sleeping. You will have no friends among the mammals or the birds.”
And that is why Bat doesn’t have any friends.
(The morale of the fable: Choose your friends carefully and remain faithful to them.)