You were walking through Viridian Forest on a search for Pokemon, when you suddenly see a Butterfree fluttering around. You get excited and run at it without thinking, scaring the Butterfree and making it use Sleep Powder instinctively, putting you to sleep.

When you wake up, you're inside of it's home on top of a really big tree, the top base of it being circular and covered in leaves, berries, and other Bug Pokemon. The Butterfree is right next to you.

"Free!" It said excitedly