This story is a sequel to Sonic The Hedgehog x My Little Pony: The Final Act

Longclaw left a message for Sonic and Sunny, where she declared she met Argyle and saw the family blanket he's been watching over for 10 generations.

However, how did Longclaw meet Argyle? And why did he accessed to save the message for his own daughter and Sonic? Find out in this story where the past before Sonic and Sunny's birth is revealed, while Sonic and Sunny themselves create a bond that unites them as siblings.