Serafall is very affectionate towards her younger sister and is willing to go to extreme extents just to protect her. She will often embarrass Sona with her childlike personality. Sona herself also cares for her sister, believing that it is her duty to take care of her sister so that she does not get influenced from bad things.
As she has weird tastes like her younger sister, she really likes the cakes that Sona makes that have 'destructive level' tastes as described by Issei and will not hesitate to punish those who openly dislike them, because it will break her younger sister's heart.
Serafall and Sirzechs are shown to be on a friendly relationship. She is also part of the Satan Rangers along with the other Four Great Satans and Grayfia, and wears the pink outfit when playing along as the Satan rangers.
Their relationship goes back to when their younger sisters, Sona and Rias, were children who would often play together at the Gremory Mansion, and she and Sirzechs would watch over them, occasionally arguing amongst themselves about whose sister is cuter, ending up with Sirzechs' mother, Venelana, scolding the both of them.
They haven't interacted too much yet are shown to be on a friendly relationship, but they are both part of the Four Great Devils, and the Satan Rangers.
They haven't interacted too much yet are shown to be in a friendly relationship, but they are both part of the Four Great Devils, and the Satan Rangers.
Rias has been best friends with Sona since they were young, and is shown to have a somewhat strained relationship with Sona's sister, Serafall. She is willing to come through for Serafall when it matters or at least for Sona's sake.
Serafall has a small feud with Issei who also has a children's television show in the Underworld that competes with her own show, although she generally gets along with him.