>>29075503Giratina's a misunderstood loner rather than an evil edgy monster, although sometimes those two can blend over a bit. It was banished for being too violent, supposedly, or it lives in the Distortion World because it created it to keep the real world stable depending on which information source you rely on, but either way it arrives at the end of Platinum to stop Cyrus from destroying both worlds when the Lake Trio aren't strong enough, since it knows both worlds rely on each other to survive. The distortion world bleeding over into the real world is an unintended side-affect of stopping Cyrus, rather than an intended goal, and I think most of the journey through the Distortion World is to test by Giratina to see if people really do want the world to keep on going, or if people want Cyrus' dream to come true.
So it's a little angsty but not evil or edgy by any means.