Athena
“Oh dear, I'm not telling you to do it, I'm just saying that maybe what you're thinking of doing isn't the best choice”
Nicknames: Thea, Miss Know it All
Species: 1/2 Lunacorn, 1/2 Unicorn
Parents: Twilight Sparkle and Tempest
Siblings:

Dusk Shine
Comet Glory

Special Talent: Future Vision. Athena's magic is strongly linked to future vision, she is able to peek into the various possible futures, with this she can give advice to guide others down a happy path.
Occupation: Advisor
Place of Birth: Nox Regnum
Place of Residence: Ponyville

Personality/Background:
Athena is a mostly shy mare, she often keeps to herself when she can and prefers the company of one or two ponies at most. She grew up as the youngest of her siblings, protected by her parents and older siblings. Athena's childhood was filled with many creatures trying to be friends with her, something her siblings also had to deal with. Athena is a kind mare, even after some of her past experiences, she is still willing to give others a chance, to the behest of some of her friends.
Athena's occupation as advisor comes with its own issues, sometimes she often has visions of other people's future and often, somehow, has to find and warn them of what she's seen. These visions usually happen in her sleep or when she least expects them, and when they do happen, she's left exhausted due to the amount of magic it exerts. Unluckily, she did inherit Twilight's workaholic behaviors, luckily though, she does have Snow Storm.
Relationships:

Athena has a close relationship with her family, even though she may not be an alicorn, her siblings adore her to bits. They often find time to hang out and end up giving each other advice on any problems they're dealing with.
Athena absolutely loves her mothers, while she does have a god relationship with them, she does sometimes feel inadequate, considering Twilight is an alicorn, Tempest is a trained and skilled warrior and her two older siblings are alicorn twins. All this sometimes gets to her and she tends to shut it out with work.
Athena's closest relationship other than the ones above would be her close friendship with Aphrodite, contrary to public belief, Aphrodite is loyal to those she considers close and will hurt you should you lay a hoof on them.

Extra:

Athena's memory is on-level with Twilight's, they both have impeccable memory, going as far as remembering events from 4 years ago.
Unlike her family, Athena isn't tall, she's actually the second shortest in the family, the shortest being her grandmother, Twilight Velvet.
Athena's future vision sometimes manifests itself as a sort of sixth sense, making her 'gut feeling' more accurate, she got help from Pinkie Pie to tune herself with it.