Hausos

They put Hausos in Fate... yes, the Proto-Indo-European dawn goddess Hausos. Her. 

She's a rider because of the solar chariot, and because of the way Proto-Indo-European works, she's a homunculus created to be a divine construct. She's not actually a real goddess since Proto-Indo-European never necessarily existed, but rather has the semblances of multiple Indo-European dawn goddesses grafted and integrated into her to create an ideal and homogenous "common denominator". She'd like to think she's just as powerful as the real thing, but since the real thing is only a concept created for comparative study, it's hard to quantify her abilities. A lot of her actual identity is unknown and muddled because of being a homunculus created/designed to be a multipurpose dawn goddess vessel, so she doesn't always feel like her own person. This goes without saying, but she's plural, and the alters in her system are the distinct spirits of the dawn goddesses compiled to create her. She wasn't actually summoned, and her body is physical. She's got the same thing going on as Mash does, but it's way more fucked up. 

Her official name as a homunculus project is H₂éwsōs but she just goes by Hausos because it's a lot easier and she likes it better. She'll respond to just about every reflex of Hausos as well. 

Personality-wise, she's narcissistic and a playful lazy spoiled princess type with a lot of big sister energy. She's really nice and actually is a big sister to the Divine Twins, who are both ~12 and also rider homunculi. They love her and look up to her. She loves to sleep and make people do all the work for her, and enjoys playing up the damsel in distress trope despite being able to take care of herself because she's hot. She really loves to dance, and is extremely good at it. She's also an amazing singer but few people know because that's the only thing she's shy about. She also really likes flirting with people and flustering them because it's fun. 

I still have no idea who her master is but she's kind of her own Noble Phantasm. It's called Daughter of Heaven and it's a big buster attack where she gracefully dances to call upon the rising sun to smite her enemies. 

I ship her with Ozymandias. They fight a lot to prove their worth to each other at first, but they come to recognize and respect each other as equals and also... lovers. As they say, sun god 4 sun god, narcissist 4 narcissist, and rider 4 rider. Hausos is very friendly and charismatic and likes to hang out with the entire gang of Fate Narcissists, especially the golden ones like Gil, Ozy (as previously mentioned), and Nero. Of course, she's also friends with Dyeus, who came from the same batch of homunculi. 

One of her casual outfits includes a red leather jacket and is very stylish biker punk. You can draw her in anything, she loves dressing up.