Speed-o'-Sound Sonic/Relationships

Saitama
Speed-o'-Sound Sonic views Saitama as his eternal rival and vows to defeat him. Saitama views their one-sided rivalry relationship in a nonchalant manner. He doesn't mind Sonic's persistence and their continuous 'battles', even goes as far to encourage Sonic to do his best. However, he would grow irritated if Sonic starts to bother him during important activities or causing a havoc around others.

According to Genos, Sonic is one of the few people who recognizes Saitama's true strength. This recognition is what caused Sonic to stop working and continue training in order to surpass Saitama. This recognition and dedication, as well as declaring Saitama a rival and admitting defeat at his hands, indicates (in his own way) a form of respect that Sonic has for Saitama.

Genos
Due to his obsession with Saitama, Genos despises Speed-o'-Sound Sonic. He also considers Sonic a rival and a reason to become stronger.

Puri-Puri-Prisoner
Sonic's relationship with Puri is differs from his relationships with other heroes, while Sonic genuinely respects Puri's physical strength he otherwise thinks of a fool and a weirdo.

Hammerhead
Due to Sonic killing all his followers Hammerhead despises Sonic.