Primrose and Enzian both have black hair like their mother (I went with the default look for Selene) and green eyes like their father. Primrose wears her hair in a bob and prefers cute fashion in pastel colors. Her main color scheme is sky blue and white. In fact, when she was younger, she wore her hair long and looked an awful lot like her aunt Lillie! Enzian inherited his father’s cowlick and seems to have perpetually messy hair. He doesn’t really care much what he wears, since he’s usually running around outdoors and getting dirty. His jeans seem to always have tears in the knees.
Both Prim and Enzian are dark mages (mediums, have an affinity for ghosts, etc) which they inherited from their mother. While Enzian loves ghosts and exploring haunted places, Primrose is terribly afraid of them. I know that part of her character arc is learning to overcome that fear, which is why I gave her Rowlet as a starter, since it eventually gains a ghost typing when it evolves. I also know that Enzian has a Mimikyu who he likes to play pranks with. Since the two of them are both too young to go on their journeys at the current point of the story, I’m not sure what their other pokémon will be!
Gladion is a stay-at-home dad in my ‘verse, so I think both the kids get along better with him just because they are more used to him. However, they definitely love their mother as well, and look forward to the times when she comes home from her busy work as champion. I will say that Selene and Primrose have a bit of a strained relationship, though. Prim feels like she can’t connect to her mother because of her fear of ghosts and Selene’s close relationship with them. She fears that she has little in common with her mother and that she won’t be able to grow close with her as a result. This fear also impacts her relationship with her little brother, since Enzian is quite different from her as well. I would say that Gladion is the family member Primrose is closest with. Enzian gets along equally with all of them, since he’s the type of kid who is very easy going and can make friends with anyone. Enzian is also particularly close with his cousin, Kou, and the two hang out pretty frequently. Primrose is best friends with Kiele (Kiawe and Mallow’s daughter) and Victoria (Lana and Sophocles’ daughter) and the three of them are very tight-knit childhood friends.