While he's still rather crass about it, whenever Seiya actually expresses gratitude or appreciation for Rista, Elulu, and Mash is rather sweet. In particular is his saving Elulu from becoming Igzasion. Igzasion would have been a major boost towards defeating the Demon Lord, but he refuses to sacrifice Elulu for it, instead declaring he'll find another way to beat the Demon Lord.
Seiya managing to calm down Adenela just by being himself. She was all set to kill him for upsetting her, but all it takes is him giving her an Affectionate Gesture to the Head and telling her to clean herself up for her to 180 and forgive him, admitting she could never hurt him since she loves him. Seiya may have sounded rude, but compared to his response to dealing with Mitis later on, it's clear he didn't consider Adenela a threat and just calmed her down by being himself.
Even though he's expressed nothing but irritation with her since their first meeting, Seiya telling Rosalie to say goodbye to her father before he dies is touching. He had little reason to do this, other than to make sure Rosalie doesn't suffer Parting-Words Regret, and it's this action that gets Rosalie to finally warm up to him.
