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.

Farsale Lugnica
Farsale was the first of all humans who was strong enough and not scared to talk to Volcanica. He also asked Volcanica to help him protect Lugnica in times of need.

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.