The overwhelming majority of Bounsweet are eaten well before they get the chance to evolve, and the species is propagated, like other angiosperms, primarily by seeds contained in the fruit. But every now and then, a Bounsweet is born with sepals too tough for flying pokemon, allowing the body underneath time to develop and change shape, until at last the middle sepal falls off and a Steenee is born.
It would be entirely reasonable for someone who emerged from such deadly circumstances to be embittered by the experience, and undoubtedly there are those who, after surviving great tragedies, become consumed by melancholy and survivor's guilt. But Steenee take the opposite perspective; they are said to be the happiest of Alolan pokemon, and their costumes have inspired generations of Alolan revelers, for they consider it a miracle that they are still alive.
Imagine, if you will, surviving accidents that would ordinarily kill a man, beginning to change form, and for your doctor to assure you that you will live to be 300, and you can begin to comprehend the joy of the Steenee. Bounsweet do not resent their inevitable predation – at least, no more than any other living creature does its own morality – but simply understand it as the way of the world, and seek to enjoy their brief lives while they can; Steenee spin and jump with the joy of a virtual immortal.
Although evolution provides the Steenee with a greatly extended lifespan, however, it can not cure all their problems. In time, like all beings, they will be ground beneath the boots of fate, and to learn to stomp upon others in return. By then, their boundless joy begins to dissipate – but of course, by that point they are no longer Steenee anymore.