Outdated by Canon: Being written in 2002, Fallen Angel has some differences from later established canon:
Amy is a friendless loner. This is because she was The Smurfette in early games and wasn't associated with any characters. Sonic avoided her, Tails rarely interacted with her, and Knuckles stuck to himself.
As a result of the above, Amy's relationships with Tails and Knuckles is more negative than in canon. Amy has a distant enough relationship with Tails that she calls him by his real name "Miles". The two don't get along and see each other as rivals for Sonic's interest.