Elmesia and Elyun are cousins through Erald and Sarion. They have a very close relationship, so much so that they completely disregard their difference in class, to the point that Elyun calls Elmesia 'Ellie', much to Erald's chagrin.
Ellen sees Kaval as a good friend and bodyguard to protect her outside her home nation. They seem to get along with each other and appear as good friends in their party.
The party grew quite attached to Rimuru and began to refer to him as Danna (Benefactor). He even gave them parting gifts, of equipment and 10 pieces of the restoration medicine. They get along well with each other.
She gets along well with Shion even going so far as sharing a bath with her, Shuna and Milim. Shion's death lead to Ellen decision to move to Tempest along with Kaval and Gido.