Despite Anon being an obviously sentient being welcomed by the Equestrians as an equal, his alien appearance and mannerisms means Fluttershy couldn't help but subconsciously see him not as a pony, but a creature, a creature she needed to love and befriend like the rest. Unfortunately, anon didn't realize at first what Fluttershy turns into when a creature doesn't love her, and he rejected her advances.
One day Anon heard someone screaming for help in the Everfree Forest. He ran to see what had happened, only to see a raven with its beak open, warbling out screams with its mimicry. A flutter of wings sounded behind him. Anon turned around, and there she was.
"Oh anon, you poor poor creature. You need a good caring home so badly, but you won't let me help you. That's OK, sometimes loving animals means doing things to them they don't want." Her eyes were bloodshot and sunken with a terrible twitch. It looked like she hadn't slept in days.
"Look Fluttershy, I already told you I'm a fully functional person. I have my own home and can take care of myself..."
"NO! You are in desperate need of love and care and I WILL take you in and I WILL LOVE YOU!"
She sprang for Anon, her front hooves colliding with his head. Anon staggered upright and shoved her back before sprinting off into the trees. He could hear her wings beating behind him. He pushed himself harder, and began to hear her pant. Heavier and heavier her breathing became, until she fell behind and disappeared in the trees. Relief filled him as he stopped to hide behind a dead trunk. She wasn't athletic enough to catch up to him.
When Anon's breathing steadied, he listened carefully. Nothing but some song birds and bugs. He peeked his head out. Nothing
Anon began to creep his way through the woods. He had no idea where he was anymore, but the sun gave him some clue of which direction to go. As he moved, Anon began to pick up the pace when there was no sign of that crazy mare.
Anon heard wings and stopped dead, but it was just a little songbird on a branch above twiddling a little song. Anon chuckled a little, until the bird looked straight at him and gave a loud screech. Larger wingbeats came crashing through the brush with an angry snort. Anon tried to run but got tangled in brambles and instead dove into the bushes to hide.
"Anon! I know you're here my pretty! Come on anon, please just... COME OUT ALREADY!"
Anon clung to the brush. The mare whipped around in circles, her deranged eyes scanning every nook and cranny.
"Oh, i guess Anon isn't here. I'm sorry for disturbing you woodland creatures. I'll be leaving now." She said in a strangely soft voice. Her hooves pattered off into the distance.