Rosinante (corazon) was an Akuma no Mi user. He ate Nagi Nagi no Mi (ナギナギの実), he was a “no sounds” man.
Vergo was first Corazón in Donquixote Pirates.
Rosinante took Law with him to search a cure of Law’s illness.
Nagi Nagi fruit can erase sound.
Rocinante is the second generation Corazon, he has ties to Sengoku and is trying to stop Doflamingo!
He’s going to put his mission on hold for now to treat Law.
No matter where Rocinante takes Law, Law is treated with spite and would not treat him.
Eventually the government tells Rocinante to report.
Roci goes on a rampage for Law.
He says when Law stabbed him, he felt no pain. He sheds tears and tells Law you are the one that felt pain, not me, poor boy..
Half a year later, he gets a call from Doflamingo….
Meanwhile, while Roci put his mission at pause to find treatment for Law, Vergo reports to Sengoku, and tells him he wishes to be transferred to G5.
It’s likely Rocinante’s treason was revealed to Doflamingo…
The realname of Roci is Donquijote Rosinante – Marine Commander. That’s why he has ties to Admiral Sengoku