Gravis and Mortis weren't exactly sure how they should feel about Orpheus' presence here.
The reason why they had stopped having contact with him was due to all his lies back then. They could understand Orpheus' reasons for telling those lies, but his methodical approach of trying to keep up their relationship destroyed the purity of a familial bond.
Mortis had a cold disposition towards Orpheus due to his demeanor that valued honesty above nearly everything else.
Gravis had been uncertain, and he wanted to have some more time to make a decision.
But now, Orpheus had returned. Even more, according to what Orthar said, Orpheus was responsible for dealing with nearly 50% of Gravis' debt.
On top of that, Orpheus had probably helped the Myriad Sect to get through the past 15,000 years of warfare.
Lastly, Orpheus had saved Gravis' and Mortis' lives right now.
It was becoming incredibly hard for Gravis to dislike Orpheus right now.