Veronica is Silvia's eldest sister, and in many ways her greatest nemesis. Silvia was terrified of Veronica for most of her life because of Veronica's harsh training methods, though she seemed to respect her greatly.
Silvia is always embarrassed and irritated by her father's insane hijinks.
Silvia seemed to at one time idolize her big brother, and even after she believed him to have committed the act of dragonslaying, she cared for him deeply.
She was initially hostile to him even slapping him after an incident and berated him for not having a dragon. This angered him and he challenged her to a race where he wagered that she would apologize to him and she accepted it. Despite her winning the race, she still searched for him the day after and apologized to him once his dragon was born and realizing she went too far in her statement.
She developed respect for him after he shows some new skill, which caused her to become attracted to him for a while during the series because of his kindness and traits that he possesses, and the things he accomplished during the time with her. Silvia finds out the truth about Ash during Volume 5, that he was the same boy that saved her, and gave her that Dragon and she has immensely cherished memories of this boy, and loves this boy dearly.
Silvia rushes into the Forest to find Ash, and after locating him she confesses to him that he is the boy that saved her in the Forest during that time, which he also recalled. Silvia then stated that because of that event and their time together, she loves him dearly and kisses him passionately. She swears to Echo that Ash will be her lover, and nothing will stand in her way even if she is the Princess of the Dragons.
The relationship has now become intimate because of the kiss that was given to Ash was of an intimate adult variety, and Eco was furious in seeing this happen, and tried to get Silvia off of Ash because it was becoming too hot of a scene to handle.
This event happened in Volume 5, and it has changed the relationships between Eco and Silvia forever. They are friends but they are fierce rivals because Silvia desires him as much as Eco, and a bitter love war has started that will not cool off because Silvia said that she will not back down on this ever.
She is a close friend but now they are bitter rivals for the affections of Ash because she will not give up on Ash after she found out the truth, and she said that she will fight with Echo with everything she has to take him, and she will not back down in this manner because this happened on Volume 5, and Echo will have to fight with everything she has to keep her away because Silvia is as serious as Echo with Ash right now.
Silvia didn't think much of Jessica and the latter didn't really have an opinion of her in spite of her being a princess which gives her a higher status. However, Jessica did protect Silvia from Avdocha's terrorist subterfuge. This act surprised Silvia who tried her best to save her before she worried for Jessica.
Ever since, the two have grown to respect her and get along better even if Jessica also sees Silvia as a rival for Ash's affections. Silvia is also one of the few to know the truth of Jessica's true family status after Rebecca Randall told her but doesn't try to reveal this.