I'm just thinking every now and then if all the voidborn are necessarily evil? Some don't really have ULTIMATELY lethal habits.
Example being that 
seems to only go for those that seem to pose a challenge, and have something that he could benefit from. Would it actually be possible for them to have rational thought? (This excludes 
and 
since Rek acts like a natural creature, while Cho intentionally wishes to devour everything.)
Well the Void isn't really evil as far as we know, or anything for that matters; it works for its own benefit. Creatures from the Void have their own individual purposes, and whether that's down to the Void's design or their own choices is up in the air right now. Cho'Gath stands out among the void's invaders as a creature who actively takes pleasure in tormenting humans, and so while humans might apply things such as evil and malice to his actions he doesn't work by the moral codes and cultural structure humans do, so really he's only evil by human definition.
The problem the Void has always posed has not been in being a force of conflict as in Runeterra and the Void go to war, but rather that the Void actively pushes its way in to Runeterra and is competing with it in a weird way. The Void's energies don't have the most positive effect on Runeterran life, and so exposure to the Void is naturally dangerous for Runeterra, but that doesn't mean the Void and Runeterra have always been in competition like this.
If we assume that the Icathians were the first or one of the first human civilisations to dabble in Void magic then it stands to reason that the Void didn't always connect to Runeterra in the way it does now. I personally view the connection in a manner more akin to the Void bleeding over in to Runeterra, although forces within the Void might have some active goals concerning its new neighbour.
I've long thought that the Void is a physical planet of some kind in a dark universe, and because of this its life has to operate differently to survive, having to constantly cannibalise anything within their universe to keep going, unlike Runeterra where the cycle of life is perpetuated by light from the sun and other factors. It personally makes sense for me if the Void is trying to consume Runeterra physically not out of malicious intent but of a natural need or else that world and all the Voidborn living there will die, and the Voidborn's purposes are all in line with the goal of being able to assimilate in to the environments of other worlds to claim them as territory for the Void to consume.
Long story short the Void's got about as much chance of being evil as it does have being good, and given the nature of the Voidborn we've seen it all works in manners much different to Runeterra, but overall with a focus on working towards the Void's best interests.
Well most void champs actually seem to act on instinct,I mean kog'maw wants to feed,Vel'koz wants to learn,kha'zix wants to evolve and rek'sai simply acts like an animal,thus I'd say their actions aren't anymore evil than those of a wild animal.
I mean if you'd get attacked by a lion,would the lion be evil?
Though cho'gath seems to be really malicious,but that could be simply because cho was released at a time where they had no idea what the void really is. Similar Kha'zix seems to have evolved a sadistic streak as well,so I guess he could also be considered evil,but that is hard to judge.
To me, Kha'Zix and Vel'koz seem to be the only ones that have much hope of reasoning. Kha's pretty dangerous, but he doesn't really know better. Depends on what he eats. If he eats a few more humans, he'll probably get some degree of reasoning.
The void are not evil. The concept of evil is restricted to humans.
Chaotic, not morally bound, feral, instinct, etc.
That's the void, IMO.
The number one aspect of it are the 'not morally bound instincts'. Learning, consuming, adapting, etc depending on which being it is.
Rek'Sai is actually a really poor example of a void creature. Doesn't really fit with the rest, imo. Should have just been a monster that lived under the Shurima desert, not a voidborn.
Only Cho seems to be clearly evil
