I wonder why Aquarius is so mean to Lucy?

because... aquarius is mean to everyone.... except scorpio.

As that it has badly humor xD

welll....that remains undecided.but aquarius is naturally very bossy and arrogant (unlike lucy!!)and she doesn't like taking orders.it is shown many times that while washing away lucy's enemies,she washes away lucy too!!

OR..
maybe she's jealous of lucy because deep down she knows that lucy is much much prettier and decenter and smarter than she'll EVER be!!

i think because
lucy always lost the key

well am gona sound like a goodie two shoes but i think deep deeeeeep very deep inside aquarius dosent hate lucy (and its mostly because aquarius dosent take orders )

Aquarius hate all girls

Because Aquarius Hate girls..haha

-Natsu Dragneel

may be because acquarius always wanted to be with her boyfren and really doesnt like getting disturbed.

i think that aquarius hates girls

she just want to teach lucy some lesson hahaha

hmm.i dont know but she is really annoying.But come to think of it aquarius is my celestial spirit according to my birth fecha !

I think it's because she doesn't have much trust in Lucy to look after her key. I also think it's because Aquarius misses Lucy's mother so much.

Uhhhh maybe it's because she is trying to get Lucy to find a boyfriend quickly...

It's a simple answer

TOUGH LOVE

In my opinion Aquarius hates Lucy b/c the girl is a reminder of the Lucy's mom, whom Aquarius loved deeply and cared for. Instead of dealing with the grief, it seems like Aquarius transferred that pain into spite. Aquarius proves she loves Lucy deep down, she just doesn't know how to mostrar it