They weren't evil, Giratina was sure of it.
Sure, many people made them out to be it. God knows how many times particularly nasty humans tended to make them out to be the bad guys, simply due to their natures.
Of course, for a while, Kyurem was looking to win "Most Evil Being in Creation" for a while, what with the whole "eating every living thing" complex it had, but that had ended when their forced fusion with Reshiram and Zekrom returned some semblence of sanity back to them.
In any event, Giratina knew that they weren't anything near as evil as people thought. Hell, even Darkrai and Yveltal were just completely misunderstood and had impossibly uncontrollable powers. If someone you never met caused nightmares just by standing around and destroyed life by waking up, you'd think--
Wait, that was a terrible example.
Giratina sighed, and one of the inverted plants collapsed. Zygarde and Mewtwo looked up from their vantage point on the ceiling, where they were apparently looking at some pictures Mewtwo had taken during their travels. After discovering Zygarde deep in the Terminus Mines, the two had struck up a friendship mostly based on their mutual like for the natural environment.
Kyurem, Genesect, and Darkrai didn't pay attention.
Yveltal, being the closest to Giratina (having been perched on the same platform Giratina was coiled up on), was the first to react to Giratina: they leaned against Giratina's tentacle-like wings and gave a low, screech-like trill. Giratina closed their eyes and let the comfort of the feeling of oblivion wash over them.
After a bit, Darkrai excused themself and exited through a puddle to Newmoon Island. Kyurem, understanding, helped Genesect (who was still experiencing some random outbursts -- one of them would have to find either the head scientist or the crown prince, and fast) through a reflective glass in Genesect's abandoned labratory, before going through a piece of ice to the Giant Chasm.
Mewtwo and Zygarde left together, not heading to Terminus or Cerulean Cave, instead heading through a random mirror. Giratina scoffed, and another pool of water formed. So the two were going to travel? How like Mewtwo, but quite unlike the hermit-like Zygarde.
Well, if anything, Mewtwo was a good influence on them.
This left Giratina and Yveltal alone.
Two beings. One of Antimatter and Annihilation, the other of Death and Oblivion. Both stared into the limitless yet finite space of the Distortion World. Neither were concerned. Giratina uncoiled and took wing, and Yveltal followed.
This was how they spent their time. Many people did not think that the Bird of Desolation would enjoy simply flying around in a game of tag, but then again, many people also thought that the Dragon of Reversal was a true being of evil.
It was as Zygarde would say: no one was truly evil in this world.
Eventually, Yveltal did catch Giratina, and the two landed near a pool of water. Yveltal looked into it, and Giratina sent ripples through the pool, forming the image of a rural Kalosian town.
Yveltal kissed Giratina goodbye.
It was a simple gesture. An exchange they both had done several times. Yveltal pressed their beak against Giratina's head and gave it a small lick. In return, Giratina
would reciprocate. This is how they kissed. This is how they expressed their mutual affection for each other.
Giratina kissed Yveltal back.
Yveltal disappeared into the pool of water, and Giratina was alone.
Giratina knew that none of them were truly evil. Yveltal was proof.