Volcanica/Relationships

Satella
Volcanica seems to hold himself responsible for the events that had transpired 400 years ago, though it's not specifically stated why he blames himself. He is also shown to have been rather close to the girl as when reminded of her, his eyes were full of sorrow and regret. As what Volcanica said, "they" cannot rise their heads in front of Satella and if Satella got hurt, it was Volcanica who would be blamed.

Farsale Lugnica
Farsale was the first of all humans who was strong enough to not cower before the Divine Dragon. He also asked Volcanica to help him protect Lugnica in times of need. They seemed to have been sharing a rather close and friendly relationship as Volcanica was speaking rather fond of him, during his faceoff with Emilia in Arc 6's climax.

Flugel
Volcanica mentioned he served as the overseer of the third trial of the Pleiades Watchtower because he was bound to a covenant. This covenant was most likely with Flugel.

Echidna & Roswaal L Mathers
Volcanica is the one that kept Echidna's soul in her grave, which was also the reason Roswaal wanted to kill Volcanica.

Patrasche
Upon meeting her, Volcanica was somehow able to recognize who Patrasche was.