Im Just Some Fucking Muggle

Ominis is gentle, protective. He would love you so deeply, having a connection to who you are through your shared experiences. He would be affectionate but not prone to public displays, enjoying private moments alone to show you his feelings.

Sebastian would be the polar opposite, the charmer. Eager to please and tell you how pretty, how gorgeous you are, and show the world that you're his. Protective but also easily jealous, he'd place a greater emphasis on the physical aspect of your relationship.

Hell is full of good meaning and wishings 

Don’t think about Ominis figuring out he mastered the levitation charm by feeling around in the air in front of him until his fingers meet the soft edges of the feather. Or how brightly he smiles when he does it.

Don’t think about Ominis teasing the first-years looking for mermaids as a way to cope with how he felt in his first year with everyone else looking for them and him just waiting on the sidelines, ears piqued, hoping to at least hear one.

Don’t think about Ominis having to hold on to Sebastian every time the stairs start moving with them on.

Don’t think about Ominis being excluded from flying class because nobody would trust he wouldn’t hurt himself on a broom and him not even arguing about it, telling himself he’d rather leave that sort of thing to Imelda. Sebastian still sneaked him out to fly at night on borrowed brooms.

Crucio

MC: Agreed... It's quite nice actually.

Ominis:

MC:

Ominis: We should check on Sebastian.

MC: Urgently.

Sebastian: Sorry for being rude earlier.

Ominis: Sorry I used facts to explain why you were wrong.

Sebastian and MC: We have a problem.

Ominis: Sebastian, no.

MC: Mistlefoe.

Due to the Gaunts being Parselmouths and Parseltongue being spoken almost exclusively amongst each other, there are typically snakes on the property, so Ominis grew up around them. I imagine he was quite lonely as a child, being the only one in his immediate family that viewed the world the way he did, so I have a feeling he likely talked to the snakes a lot. In a way, they were his friends. He felt he could understand them and they could understand him.