I will always love Yasha so much as a rival character.
Always doing what he believes is right even if he finds himself on the wrong side of a divine cause. Making the ultimate sacrifice for what he believes in order to try and free the world from suffering. Yasha was always trying to do the best for the world and never wanted to rule as a god over others. Always seemingly cool-headed but still ruled over by his mantra of melancholy while also trying to ensure a world without it, inflicting so much suffering yet never reveling in it and knowing the weight of the losses he's given and made for the great rebirth. His brother-in-law and in-multiple-arms was able to put an eternal scourge to the world to rest, but only for a time, there will still always be suffering in the world so long as Vlitra and the Gohma plague Gaia... So he made the ultimate selfless sacrifice voluntarily for the sake of the greater good.
Only to see Asura come back with the strength and righteous anger to challenge the very cause Yasha supported and committed countless atrocities for. All of that loss, all of the guilt of the people that were used as a means to an end; his sister Durga, his niece Mithra, his brother Asura, and he was able to save the world without the need for sacrifice? Yet Yasha doesn't lose determination. He like Asura now uses his manta to fight for the sake of a true purpose, using a millennia of grief and sorrow to challenge the cause that was twisted by the other deities. And he and Asura succeded against Vlitra! but turns out, all the suffering of the world was a cyclical test made by ACTUAL GOD. And to make it worse, THE FUCKING GOHMA ARE STILL AROUND.
Yasha questioned the purpose of existence not once but twice over. Especially after the absolute bombshell of the second existential crisis, he understandably doesn't have much left in him to go on and even questions if anything they did truly mattered. Yet Yasha still doesn't lose resolve completely. He knows he's not Asura, someone who through the true unflinching purpose of his wrath can save the world and bring back Mithra. He fights back against the seeming futility of their actions and makes a choice only he can in allowing Asura to do what he can't, making one final selfless sacrifice. He entrusts Asura with the embodiment of the Seven Deities' cause, now stripped of all the meaningless and perverse sacrifice that came with it, and uses it to empower Asura's wrath, made all the more pure by giving Asura his own will through Yasha's reactor.
Asura and Yasha's final fight between each other is Yasha fully embracing his emotions like Asura one final time. The existential dread of his existence and the weight of his actions through it all, the sorrow of entrusting this impossible task to Asura even if Yasha trusts him to see it through, the pain of fighting his own brother in his final moments. Yasha fights Asura until the very end, knowing his brother has the power to save the world and their family.
And at the very end of his life... Yasha, the demigod of melancholy, dies with a smile on his face.
